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>

src/web/api/player.ts

@@ -268,7 +268,7 @@ export function createPlayerRouter(
         // the sequential retry path, which still has a chance.
       }
       if (queueable.length === 0) {
-        res.json({ message: `Loaded ${totalCount} songs but none were playable (likely copyright/region restrictions).` });
+        res.json({ ok: false, message: `歌单 ${totalCount} 首歌曲均无版权可播放（区域/版权限制）` });
         return;
       }
 
@@ -300,12 +300,12 @@ export function createPlayerRouter(
 
       const playing = queue.current();
       const loadedMsg = queueable.length < totalCount
-        ? `Loaded ${queueable.length} of ${totalCount} songs (rest are copyright/region restricted)`
-        : `Loaded ${queueable.length} songs`;
+        ? `已加载 ${queueable.length}/${totalCount} 首（其余区域/版权限制）`
+        : `已加载 ${queueable.length} 首`;
       if (started && playing) {
-        res.json({ message: `${loadedMsg}. Now playing: ${playing.name}` });
+        res.json({ ok: true, message: `${loadedMsg}，正在播放：${playing.name}` });
       } else {
-        res.json({ message: `${loadedMsg}, but couldn't start playback.` });
+        res.json({ ok: false, message: `${loadedMsg}，但无法开始播放。` });
       }
     } catch (err) {
       logger.error({ err }, "Play playlist failed");
@@ -330,11 +330,11 @@ export function createPlayerRouter(
       bot.getPlayer().resetFailures();
       const ok = await bot.resolveAndPlay(queue.current()!);
       if (!ok) {
-        res.json({ message: `Cannot play: ${song.name || song.id}` });
+        res.json({ ok: false, message: `无法播放「${song.name || song.id}」（区域/版权限制）` });
         return;
       }
 
-      res.json({ message: `Now playing: ${song.name || 'Unknown'} - ${song.artist || 'Unknown'}` });
+      res.json({ ok: true, message: `正在播放：${song.name || 'Unknown'} - ${song.artist || 'Unknown'}` });
     } catch (err) {
       res.status(500).json({ error: (err as Error).message });
     }