feat(mobile): UI-01 album cards, photo grid and full viewer

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

apps/mobile/test/pages/albums_tab_test.dart

@@ -1,8 +1,9 @@
-/// 相册列表页签 widget 测试（P3 Task 4；UI-01 Task 3 起覆盖封面卡片样板）。
+/// 相册列表页签 widget 测试（P3 Task 4；UI-01 Task 3/4 覆盖封面卡片与
+/// 响应式列表）。
 ///
-/// 覆盖：封面卡片样板（封面占位/标题回退/时间场地行/公开与上传徽章/
-/// 令牌与四开关移除）、关闭状态徽章、封面加载失败替代图、游标加载更多
-/// （第二页携带 cursor）、空态文案、首屏错误 + 重试恢复。
+/// 覆盖：封面卡片（封面占位/标题回退/时间场地行/公开与上传徽章/令牌与
+/// 四开关移除）、关闭状态徽章、封面加载失败替代图、响应式单/双列、空态
+/// CTA、游标加载更多（第二页携带 cursor）、首屏错误 + 重试恢复。
 library;
 
 import 'package:dio/dio.dart';
@@ -14,6 +15,7 @@ import 'package:photo_live/core/error_codes.dart';
 import 'package:photo_live/features/albums/providers.dart';
 import 'package:photo_live/l10n/app_localizations.dart';
 import 'package:photo_live/pages/albums_tab.dart';
+import 'package:photo_live/pages/album_form_page.dart';
 import 'package:photo_live/ui/components/photo_thumbnail.dart';
 
 import '../helpers/fakes.dart';
@@ -45,6 +47,12 @@ void main() {
     await tester.pumpAndSettle();
   }
 
+  /// 固定逻辑宽度（dp=1）。
+  void setSurface(WidgetTester tester, Size size) {
+    tester.view.physicalSize = size;
+    tester.view.devicePixelRatio = 1.0;
+  }
+
   testWidgets('封面卡片样板：封面占位 + 标题回退 + 时间场地 + 公开/上传徽章', (tester) async {
     final adapter = FakeAdapter(
       (o) => o.path == '/v1/albums'
@@ -101,6 +109,67 @@ void main() {
     expect(find.byIcon(Icons.image_outlined), findsNothing);
   });
 
+  testWidgets('响应式列数：390 宽单列 / 900 宽双列', (tester) async {
+    final adapter = FakeAdapter(
+      (o) => o.path == '/v1/albums'
+          ? (
+              200,
+              cursorPageBody([
+                albumJson(id: 'alb-1'),
+                albumJson(id: 'alb-2'),
+              ]),
+            )
+          : throw StateError('unexpected ${o.path}'),
+    );
+    final client = clientOf(adapter);
+
+    // 手机宽度（390）：单列，两卡片同宽同行不可见。
+    setSurface(tester, const Size(390, 844));
+    await pumpTab(tester, client);
+    final card1 = tester.getRect(find.byType(PhotoThumbnail).first);
+    final card2 = tester.getRect(find.byType(PhotoThumbnail).last);
+    expect(card1.width, closeTo(390 - 32, 0.5), reason: '单列占满（左右 16）');
+    expect(
+      card1.right == card2.right && card1.left == card2.left,
+      isTrue,
+      reason: '两卡片同列（垂直排布）',
+    );
+
+    // 平板宽度（900）：双列并排。
+    setSurface(tester, const Size(900, 1200));
+    await pumpTab(tester, client);
+    final wide1 = tester.getRect(find.byType(PhotoThumbnail).first);
+    final wide2 = tester.getRect(find.byType(PhotoThumbnail).last);
+    expect(wide1.width, closeTo((900 - 32 - 12) / 2, 0.5), reason: '双列均分');
+    expect(
+      wide2.left > wide1.right,
+      isTrue,
+      reason: '第二张在第一张右侧（双列）',
+    );
+
+    tester.view.resetPhysicalSize();
+    tester.view.resetDevicePixelRatio();
+  });
+
+  testWidgets('空列表 → 空态文案 + 「新建相册」CTA 进入表单', (tester) async {
+    final adapter = FakeAdapter(
+      (o) => o.path == '/v1/albums'
+          ? (200, cursorPageBody(<Map<String, dynamic>>[]))
+          : throw StateError('unexpected ${o.path}'),
+    );
+    await pumpTab(tester, clientOf(adapter));
+
+    expect(
+      find.text('No albums yet. Tap "Create album" to get started'),
+      findsOneWidget,
+    );
+    // 空态 CTA（次强调按钮）→ 创建表单。
+    expect(find.byType(AlbumFormPage), findsNothing);
+    await tester.tap(find.widgetWithText(FilledButton, 'Create album'));
+    await tester.pumpAndSettle();
+    expect(find.byType(AlbumFormPage), findsOneWidget);
+  });
+
   testWidgets('滚动接近底部 → 游标加载第二页（携带 cursor）', (tester) async {
     final page1 = List<Map<String, dynamic>>.generate(
       20,
@@ -146,20 +215,6 @@ void main() {
     );
   });
 
-  testWidgets('空列表 → 空态文案', (tester) async {
-    final adapter = FakeAdapter(
-      (o) => o.path == '/v1/albums'
-          ? (200, cursorPageBody(<Map<String, dynamic>>[]))
-          : throw StateError('unexpected ${o.path}'),
-    );
-    await pumpTab(tester, clientOf(adapter));
-
-    expect(
-      find.text('No albums yet. Tap "Create album" to get started'),
-      findsOneWidget,
-    );
-  });
-
   testWidgets('首屏错误 → 错误视图，重试后恢复', (tester) async {
     var failFirst = true;
     final adapter = FakeAdapter((o) {