feat(viewer): UI-02 heart particles, interaction notices, share and download

Task 5 (V05 §5.4/§6): decorative heart particles on the lightbox stage
(local like clicks + others' WS bursts for the current photo), compact
cross-photo interaction notices above the action bar (click to locate),
navigator.share-first share orchestration with clipboard fallback for
album and photo deep links (lang param), and download failures attributed
to the photo that triggered them. Self-echo dedup stays in the realtime
router (own batches never produce particles/notices); particles cap at
12 with visibility/unmount cleanup and are suppressed under reduced
motion; notices cap at 3 with ~4s auto-dismiss and throttled SR summary.

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

apps/viewer/src/likes/useLikes.ts

@@ -39,6 +39,10 @@ const MY_BATCHES_CAP = 100;
 /** sessionStorage 键：会话标识（每标签页会话一枚，跨刷新复用）。 */
 const SESSION_KEY = 'viewer.likeSessionId';
 
+/** 本地点击动效监听器（UI-02 V05）：每次有效点击立即通知——与批次发送/重试
+ * 语义完全解耦（不为动画补帧额外发送点赞，§6.1）。 */
+export type LocalLikeListener = (photoId: string) => void;
+
 /** 单照片状态（base=权威累计，pending=未落定乐观量，pop=动画 nonce）。 */
 interface PhotoLikeState {
   base: number;
@@ -88,6 +92,7 @@ export function useLikes(inputs: LikesInputs) {
 
   let flushTimer: ReturnType<typeof setTimeout> | null = null;
   const retryTimers = new Set<ReturnType<typeof setTimeout>>();
+  const localLikeListeners = new Set<LocalLikeListener>();
 
   function stateOf(photoId: string, seedCount?: number): PhotoLikeState {
     let state = states.get(photoId);
@@ -110,6 +115,8 @@ export function useLikes(inputs: LikesInputs) {
     state.pending += 1;
     state.pop += 1;
     queued.set(photoId, (queued.get(photoId) ?? 0) + 1);
+    // 本地点击动效事件（UI-02 V05）：仅通知订阅方（粒子等装饰层），不影响批次。
+    for (const listener of localLikeListeners) listener(photoId);
     if ((queued.get(photoId) ?? 0) >= LIKE_FLUSH_CAP) {
       flushQueue();
       return;
@@ -119,6 +126,14 @@ export function useLikes(inputs: LikesInputs) {
     }
   }
 
+  /** 订阅本地点击动效事件（UI-02 V05）：返回退订函数（订阅方随上下文卸载）。 */
+  function onLocalLike(listener: LocalLikeListener): () => void {
+    localLikeListeners.add(listener);
+    return () => {
+      localLikeListeners.delete(listener);
+    };
+  }
+
   /** 冲队：每照片一批（新 batchId）；未满防抖窗的部分留给下一窗。 */
   function flushQueue(): void {
     if (flushTimer !== null) {
@@ -213,6 +228,7 @@ export function useLikes(inputs: LikesInputs) {
     if (flushTimer !== null) clearTimeout(flushTimer);
     for (const timer of retryTimers) clearTimeout(timer);
     retryTimers.clear();
+    localLikeListeners.clear();
   });
 
   return reactive({
@@ -221,6 +237,8 @@ export function useLikes(inputs: LikesInputs) {
     /** 点击动画 nonce（每次点击 +1，模板 :key 重挂触发动画）。 */
     popNonce: (photoId: string) => states.get(photoId)?.pop ?? 0,
     like,
+    /** 订阅本地点击动效事件（UI-02 V05 粒子等）。 */
+    onLocalLike,
     calibrate,
     ownDeltaIn,
     recalibrateFromList,