fix: address all known follow-up issues except NetEase batch precheck

Surface failures + tighten edges:

1. Toast for /play-song & /play-playlist failures. Backend now returns
   {ok, message} (localized in Chinese to match the rest of the UI).
   Store stashes a notification on ok=false; new Toast.vue mounted in
   App.vue shows it for 3-5s then fades. Clicking the X dismisses
   immediately. Sits above the player on desktop and above the mobile
   tabbar on phones.

2. QQ collected playlists pagination. fcg_get_profile_order_asset.fcg
   returns max 30 per call; we now loop using has_more / short-page
   detection up to a 300-playlist hard cap. Single-call users (typical)
   exit the loop on the first iteration so no extra requests.

3. getPlayableSongIds chunking. 100 mids per request keeps URL well
   under 8KB; chunk-level errors are isolated so a transient blip on
   one chunk doesn't poison the whole batch. Returns null only when
   every chunk failed (caller falls back to sequential retry).

4. SourceTabs single-source mode now renders a small subdued "网易云"
   or "QQ" label instead of vanishing entirely, so the user always
   knows which platform's data they're looking at.

5. Hide the "我的歌单 N" count badge when N=0 — Home and Library no
   longer show "我的歌单 0" with an empty grid.

6. Auth state change invalidates fetchHomeData cache. Previously, a
   user who logged out as account A and into account B within 5
   minutes would see A's playlists. Now we always re-check auth at
   the top of fetchHomeData and bypass the TTL cache when authStatus
   has changed.

Out of scope:
- NetEase analogous batch precheck (per request).
- 60s TS3 UDP idle disconnect — that's the bundled @honeybbq/teamspeak-
  client UDP layer kicking when no server packet arrives in 60s. It's
  baked in (constant `v=6e4`) and not exposed as an option, and root
  cause is server-side or network-layer behavior we can't reach from
  here.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/stores/player.ts

@@ -63,6 +63,10 @@ export const usePlayerStore = defineStore('player', {
     bilibiliPopular: [] as Song[],
     authStatus: { netease: false, qq: false },
     lastFetchTime: 0,
+
+    // Transient notification for surfacing failures (e.g., "song not playable")
+    // to a global Toast. Bumped `id` triggers re-render of the same message.
+    notification: null as { id: number; message: string; type: 'error' | 'info' } | null,
   }),
 
   getters: {
@@ -269,9 +273,16 @@ export const usePlayerStore = defineStore('player', {
       this._syncAfterAction();
     },
 
+    notify(message: string, type: 'error' | 'info' = 'info') {
+      this.notification = { id: Date.now(), message, type };
+    },
+
     async playSong(song: Song) {
       if (!this.activeBotId) return;
-      await axios.post(`/api/player/${this.activeBotId}/play-song`, { song });
+      const res = await axios.post(`/api/player/${this.activeBotId}/play-song`, { song });
+      if (res.data?.ok === false && res.data?.message) {
+        this.notify(res.data.message, 'error');
+      }
       this._setTiming(this.activeBotId, { serverElapsed: 0 });
       this._syncAfterAction();
     },
@@ -293,7 +304,10 @@ export const usePlayerStore = defineStore('player', {
 
     async playPlaylist(playlistId: string, platform = 'netease') {
       if (!this.activeBotId) return;
-      await axios.post(`/api/player/${this.activeBotId}/play-playlist`, { playlistId, platform });
+      const res = await axios.post(`/api/player/${this.activeBotId}/play-playlist`, { playlistId, platform });
+      if (res.data?.message) {
+        this.notify(res.data.message, res.data.ok === false ? 'error' : 'info');
+      }
       this._setTiming(this.activeBotId, { serverElapsed: 0 });
       this._syncAfterAction();
     },
@@ -360,19 +374,30 @@ export const usePlayerStore = defineStore('player', {
     },
 
     async fetchHomeData() {
-      if (this.lastFetchTime > 0 && Date.now() - this.lastFetchTime < HOME_CACHE_TTL) {
-        return;
-      }
-
-      // 1. Fetch auth status for both platforms first.
+      // Always check auth status first — if it changed since the cached
+      // fetch (e.g., user logged in/out as a different account), the
+      // cached playlists belong to a different user and we MUST refetch.
       const [neAuthRes, qqAuthRes] = await Promise.allSettled([
         axios.get('/api/auth/status', { params: { platform: 'netease' } }),
         axios.get('/api/auth/status', { params: { platform: 'qq' } }),
       ]);
-      this.authStatus.netease =
-        neAuthRes.status === 'fulfilled' && !!neAuthRes.value.data?.loggedIn;
-      this.authStatus.qq =
-        qqAuthRes.status === 'fulfilled' && !!qqAuthRes.value.data?.loggedIn;
+      const newAuth = {
+        netease: neAuthRes.status === 'fulfilled' && !!neAuthRes.value.data?.loggedIn,
+        qq:      qqAuthRes.status === 'fulfilled' && !!qqAuthRes.value.data?.loggedIn,
+      };
+      const authChanged =
+        newAuth.netease !== this.authStatus.netease || newAuth.qq !== this.authStatus.qq;
+      this.authStatus.netease = newAuth.netease;
+      this.authStatus.qq = newAuth.qq;
+
+      // Cache hit only if auth is unchanged AND within TTL.
+      if (
+        !authChanged &&
+        this.lastFetchTime > 0 &&
+        Date.now() - this.lastFetchTime < HOME_CACHE_TTL
+      ) {
+        return;
+      }
 
       // 2. NetEase data: recommend playlists work anonymously; daily/user
       // playlists need login but Promise.allSettled isolates failures.