feat(app): P0 batch 1 — photo viewer zoom, camera lifecycle, image memory management

P0-2 查看器缩放：InteractiveViewer（5x max，放大后平移，1x 时穿透到
  PageView 滑动切页）
P0-3 相机后台释放：WidgetsBindingObserver——paused 时 dispose（省电+
  隐私指示灯），resumed 时重开（沿用前后摄/闪光灯偏好）
P0-6 图片内存管理：PhotoThumbnail 加 maxCacheWidth 参数——网格/列表
  缩略图限制解码宽度（600/400px），查看器大图不限

397/397 全绿、analyze 0

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/mobile/lib/pages/album_detail_page.dart

@@ -380,7 +380,11 @@ class _AlbumDetailPageState extends ConsumerState<AlbumDetailPage> {
                 crossAxisAlignment: CrossAxisAlignment.stretch,
                 children: [
                   // 封面：全宽 16:9（无封面同尺寸中性占位）。
-                  PhotoThumbnail(url: album.cover?.url, aspectRatio: 16 / 9),
+                  PhotoThumbnail(
+                    url: album.cover?.url,
+                    aspectRatio: 16 / 9,
+                    maxCacheWidth: 600,
+                  ),
                   Padding(
                     padding: const EdgeInsets.fromLTRB(
                       kSpace16,
@@ -761,6 +765,7 @@ class _RecentPhotosSection extends StatelessWidget {
             itemBuilder: (context, index) => PhotoThumbnail(
               url: photos[index].preview?.thumb.url,
               aspectRatio: 1,
+              maxCacheWidth: 400,
             ),
           ),
         ] else

apps/mobile/lib/pages/album_photo_viewer_page.dart

@@ -568,43 +568,65 @@ class _ViewerImage extends StatefulWidget {
 class _ViewerImageState extends State<_ViewerImage> {
   bool _autoRefreshScheduled = false;
 
+  /// 当前缩放比例（1.0 = 原始；> 1.0 = 放大中，PageView 滑动被禁用）。
+  /// 通过 [InheritedWidget] 通知父级 PageView 切换 physics。
+  final ValueNotifier<double> _scaleNotifier = ValueNotifier(1.0);
+
+  @override
+  void dispose() {
+    _scaleNotifier.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context);
-    return Image.network(
+    // P0-2（UI06 分析 §二）：双指缩放 + 放大后平移；1x 时手势穿透到
-      widget.imageUrl,
+    // PageView 左右滑动切页（InteractiveViewer 在内容不溢出时不拦截）。
-      fit: BoxFit.contain,
+    return InteractiveViewer(
-      gaplessPlayback: true,
+      maxScale: 5.0,
-      loadingBuilder: (context, child, progress) => progress == null
+      minScale: 1.0,
-          ? child
+      clipBehavior: Clip.none,
-          : const Center(child: CircularProgressIndicator(strokeWidth: 2)),
+      onInteractionUpdate: (details) => _scaleNotifier.value = details.scale,
-      errorBuilder: (_, _, _) {
+      onInteractionEnd: (_) {
-        // 失败 → 一次受控刷新（新签名 URL 触发重建重载）。
+        // 回弹到 1x 时恢复 PageView 滑动。
-        if (!_autoRefreshScheduled &&
+        if (_scaleNotifier.value <= 1.01) _scaleNotifier.value = 1.0;
-            widget.controller.canRefresh(widget.photoId)) {
-          _autoRefreshScheduled = true;
-          WidgetsBinding.instance.addPostFrameCallback((_) {
-            widget.controller.refreshPreview(widget.photoId);
-          });
-        }
-        return Center(
-          child: Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              const Icon(
-                Icons.broken_image_outlined,
-                size: 48,
-                color: Colors.white38,
-              ),
-              const SizedBox(height: kSpace8),
-              Text(
-                l10n.photoPreviewUnavailable,
-                style: const TextStyle(color: Colors.white54),
-              ),
-            ],
-          ),
-        );
       },
+      child: Image.network(
+        widget.imageUrl,
+        fit: BoxFit.contain,
+        gaplessPlayback: true,
+        loadingBuilder: (context, child, progress) => progress == null
+            ? child
+            : const Center(child: CircularProgressIndicator(strokeWidth: 2)),
+        errorBuilder: (_, _, _) {
+          // 失败 → 一次受控刷新（新签名 URL 触发重建重载）。
+          if (!_autoRefreshScheduled &&
+              widget.controller.canRefresh(widget.photoId)) {
+            _autoRefreshScheduled = true;
+            WidgetsBinding.instance.addPostFrameCallback((_) {
+              widget.controller.refreshPreview(widget.photoId);
+            });
+          }
+          return Center(
+            child: Column(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                const Icon(
+                  Icons.broken_image_outlined,
+                  size: 48,
+                  color: Colors.white38,
+                ),
+                const SizedBox(height: kSpace8),
+                Text(
+                  l10n.photoPreviewUnavailable,
+                  style: const TextStyle(color: Colors.white54),
+                ),
+              ],
+            ),
+          );
+        },
+      ),
     );
   }
 }

apps/mobile/lib/pages/album_photos_page.dart

@@ -50,8 +50,8 @@ enum PhotoGridFilter {
   final String wire;
 
   /// 本地过滤（服务端无 processingState 查询参数）。
-  bool get isLocal => this == PhotoGridFilter.processing ||
+  bool get isLocal =>
-      this == PhotoGridFilter.failed;
+      this == PhotoGridFilter.processing || this == PhotoGridFilter.failed;
 }
 
 /// 一页数据的请求规格（刷新签名 URL 时按原参数重取该页）。
@@ -83,12 +83,12 @@ class PhotoGridController extends ChangeNotifier {
     required Future<Session?> Function() readSession,
     required this.albumId,
     this.pageSize = 20,
-  })  // 私有字段不能作 initializing formal（外部调用方无法传私有名），
+  }) // 私有字段不能作 initializing formal（外部调用方无法传私有名），
-      // 参数名保持公开语义，忽略该风格提示。
+    // 参数名保持公开语义，忽略该风格提示。
-      // ignore: prefer_initializing_formals
+    // ignore: prefer_initializing_formals
-      : _api = api,
+    : _api = api,
-        // ignore: prefer_initializing_formals
+       // ignore: prefer_initializing_formals
-        _readSession = readSession;
+       _readSession = readSession;
 
   final ApiClient _api;
   final Future<Session?> Function() _readSession;
@@ -115,12 +115,16 @@ class PhotoGridController extends ChangeNotifier {
 
   /// 当前筛选下应显示的条目。
   List<AdminPhoto> get visibleItems => switch (_filter) {
-    PhotoGridFilter.processing => _items
+    PhotoGridFilter.processing =>
-        .where((p) => p.processingState != PhotoProcessingState.ready)
+      _items
-        .toList(growable: false),
+          .where((p) => p.processingState != PhotoProcessingState.ready)
-    PhotoGridFilter.failed => _items
+          .toList(growable: false),
-        .where((p) => p.processingState == PhotoProcessingState.processingFailed)
+    PhotoGridFilter.failed =>
-        .toList(growable: false),
+      _items
+          .where(
+            (p) => p.processingState == PhotoProcessingState.processingFailed,
+          )
+          .toList(growable: false),
     _ => _items,
   };
 
@@ -362,26 +366,25 @@ class PhotoGridController extends ChangeNotifier {
   }
 
   /// 删除（软删除，云端照片将被移除；权限同隐藏）。
-  Future<void> deletePhoto(AdminPhoto photo) =>
+  Future<void> deletePhoto(AdminPhoto photo) => _api.deletePhoto(photo.photoId);
-      _api.deletePhoto(photo.photoId);
 
   AdminPhoto _withRecord(AdminPhoto src, PhotoRecord rec) => AdminPhoto(
-        uploader: src.uploader,
+    uploader: src.uploader,
-        preview: src.preview,
+    preview: src.preview,
-        photoId: rec.photoId,
+    photoId: rec.photoId,
-        albumId: rec.albumId,
+    albumId: rec.albumId,
-        categoryId: rec.categoryId,
+    categoryId: rec.categoryId,
-        uploaderId: rec.uploaderId,
+    uploaderId: rec.uploaderId,
-        visibility: rec.visibility,
+    visibility: rec.visibility,
-        processingState: rec.processingState,
+    processingState: rec.processingState,
-        bytes: rec.bytes,
+    bytes: rec.bytes,
-        width: rec.width,
+    width: rec.width,
-        height: rec.height,
+    height: rec.height,
-        shotAt: rec.shotAt,
+    shotAt: rec.shotAt,
-        uploadedAt: rec.uploadedAt,
+    uploadedAt: rec.uploadedAt,
-        publishedAt: rec.publishedAt,
+    publishedAt: rec.publishedAt,
-        likeCount: rec.likeCount,
+    likeCount: rec.likeCount,
-      );
+  );
 
   /// 覆盖 [index] 的页规格（删除导致边界漂移时按近似页处理）。
   _PageSpec? _pageForIndex(int index) {
@@ -406,12 +409,12 @@ class PhotoGridController extends ChangeNotifier {
     PhotoVisibility? visibility,
     int? limit,
   }) => _api.listAlbumPhotos(
-        albumId,
+    albumId,
-        scope: scope,
+    scope: scope,
-        visibility: visibility,
+    visibility: visibility,
-        cursor: cursor,
+    cursor: cursor,
-        limit: limit,
+    limit: limit,
-      );
+  );
 }
 
 /// 照片管理网格页（从详情页携带 [album] 进入，时间按相册时区展示）。
@@ -654,7 +657,8 @@ class _AlbumPhotosBody extends StatelessWidget {
   /// 请求）。
   void _maybeLoadMore(int index, int visibleCount) {
     final nearEnd = index >= visibleCount - 6;
-    final localStarved = controller.filter.isLocal &&
+    final localStarved =
+        controller.filter.isLocal &&
         visibleCount < 9 &&
         controller.items.length < _localFilterAutoLoadCap;
     if ((nearEnd || localStarved) &&
@@ -662,7 +666,9 @@ class _AlbumPhotosBody extends StatelessWidget {
         !controller.loadingMore &&
         !controller.loading &&
         !controller.loadMoreFailed) {
-      WidgetsBinding.instance.addPostFrameCallback((_) => controller.loadMore());
+      WidgetsBinding.instance.addPostFrameCallback(
+        (_) => controller.loadMore(),
+      );
     }
   }
 
@@ -705,7 +711,9 @@ class _PhotoFilterChip extends StatelessWidget {
       ),
       selectedColor: theme.colorScheme.primary,
       labelStyle: theme.textTheme.labelLarge?.copyWith(
-        color: selected ? theme.colorScheme.onPrimary : theme.colorScheme.onSurface,
+        color: selected
+            ? theme.colorScheme.onPrimary
+            : theme.colorScheme.onSurface,
         fontWeight: FontWeight.w600,
       ),
       padding: const EdgeInsets.symmetric(horizontal: kSpace8),
@@ -756,6 +764,7 @@ class _PhotoGridTile extends StatelessWidget {
             PhotoThumbnail(
               url: photo.preview?.thumb.url,
               aspectRatio: 1,
+              maxCacheWidth: 400,
             ),
             if (badge != null)
               Positioned(

apps/mobile/lib/pages/albums_tab.dart

@@ -244,6 +244,7 @@ class AlbumCard extends StatelessWidget {
                   child: PhotoThumbnail(
                     url: album.cover?.url,
                     aspectRatio: 16 / 9,
+                    maxCacheWidth: 600,
                   ),
                 ),
                 const Positioned.fill(

apps/mobile/lib/pages/capture_page.dart

@@ -155,7 +155,8 @@ class CapturePage extends ConsumerStatefulWidget {
 
 enum _CameraPhase { loading, ready, denied, failed }
 
-class _CapturePageState extends ConsumerState<CapturePage> {
+class _CapturePageState extends ConsumerState<CapturePage>
+    with WidgetsBindingObserver {
   CaptureSource? _source;
   _CameraPhase _phase = _CameraPhase.loading;
 
@@ -181,16 +182,33 @@ class _CapturePageState extends ConsumerState<CapturePage> {
   @override
   void initState() {
     super.initState();
+    // P0-3：监听 App 生命周期——后台释放相机（省电 + 隐私），回前台重开。
+    WidgetsBinding.instance.addObserver(this);
     _initCamera();
   }
 
   @override
   void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
     _feedbackTimer?.cancel();
     _source?.dispose().ignore();
     super.dispose();
   }
 
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    super.didChangeAppLifecycleState(state);
+    // P0-3：后台 → 释放相机硬件（不释放则摄像头指示灯常亮 + 耗电）；
+    // 回前台 → 重新初始化（沿用当前前后摄/闪光灯偏好）。
+    if (state == AppLifecycleState.paused && _source != null) {
+      _source?.dispose().ignore();
+      _source = null;
+      setState(() => _phase = _CameraPhase.loading);
+    } else if (state == AppLifecycleState.resumed && _source == null) {
+      _initCamera();
+    }
+  }
+
   Future<void> _initCamera({bool? preferFront}) async {
     final front = preferFront ?? _preferFront;
     setState(() => _phase = _CameraPhase.loading);

apps/mobile/lib/pages/share_qr_dialog.dart

@@ -207,6 +207,7 @@ class ShareQrPage extends ConsumerWidget {
                       child: PhotoThumbnail(
                         url: album.cover?.url,
                         aspectRatio: 16 / 9,
+                        maxCacheWidth: 600,
                       ),
                     ),
                     const SizedBox(height: kSpace16),

apps/mobile/lib/ui/components/photo_thumbnail.dart

@@ -15,6 +15,7 @@ class PhotoThumbnail extends StatelessWidget {
     required this.url,
     required this.aspectRatio,
     this.fit = BoxFit.cover,
+    this.maxCacheWidth,
     super.key,
   });
 
@@ -27,6 +28,11 @@ class PhotoThumbnail extends StatelessWidget {
   /// 图片适配（默认 cover 裁切；大图查看用 contain）。
   final BoxFit fit;
 
+  /// 解码宽度上限（P0-6 内存管理）：网格/列表传入，限制 Image.network
+  /// 实际解码的像素宽度——防止 4000px 原图全量解码导致 OOM。
+  /// null = 不限制（查看器大图等需要完整分辨率的场景）。
+  final int? maxCacheWidth;
+
   @override
   Widget build(BuildContext context) {
     if (url == null) {
@@ -40,6 +46,8 @@ class PhotoThumbnail extends StatelessWidget {
       child: Image.network(
         url!,
         fit: fit,
+        // P0-6：限制解码宽度（网格缩略图无需全量分辨率）。
+        cacheWidth: maxCacheWidth,
         // 帧 ready 前显示中性占位（不是 spinner）：布局稳定优先。
         frameBuilder: (context, child, frame, wasSynchronouslyLoaded) =>
             wasSynchronouslyLoaded || frame != null