fix(pr-review): address review findings for music folder filter

- Sidebar.tsx: title={} → data-tooltip + data-tooltip-pos="right" on
  scope subtitle (CLAUDE.md rule: never use native title= for tooltips)

- authStore.ts: merge two set() calls in setMusicFolders into one atomic
  update — avoids double render on folder list arrival

- locales (all 7): remove dead libraryScopeHint key (defined but never
  rendered in any component)

- Genres.tsx: remove musicLibraryFilterVersion from effect deps —
  getGenres is intentionally not folder-scoped, re-fetching on filter
  change was a no-op waste

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/store/authStore.ts

@@ -243,15 +243,17 @@ export const useAuthStore = create<AuthState>()(
       setHotCacheDownloadDir: (v) => set({ hotCacheDownloadDir: v }),
 
       setMusicFolders: (folders) => {
-        set({ musicFolders: folders });
         const sid = get().activeServerId;
-        if (!sid) return;
-        const f = get().musicLibraryFilterByServer[sid];
-        if (f && f !== 'all' && !folders.some(x => x.id === f)) {
-          set(s => ({
-            musicLibraryFilterByServer: { ...s.musicLibraryFilterByServer, [sid]: 'all' },
-          }));
-        }
+        set(s => {
+          const f = sid ? s.musicLibraryFilterByServer[sid] : undefined;
+          const invalidFilter = f && f !== 'all' && !folders.some(x => x.id === f);
+          return {
+            musicFolders: folders,
+            ...(sid && invalidFilter
+              ? { musicLibraryFilterByServer: { ...s.musicLibraryFilterByServer, [sid]: 'all' } }
+              : {}),
+          };
+        });
       },
 
       setMusicLibraryFilter: (folderId) => {