feat: downloads, RSS, subtitles, Bangumi, watcher, stats, profile, audit

Backend
  - service/bangumi.go: Bangumi (bgm.tv) scraper for anime libraries.
  - service/episode_parser.go: SxxExx / NxE / EPxx / 第NN集 parser with
    unit tests; consumed by the scanner for tv/anime libraries.
  - service/scraper.go: provider chain orchestrator picks Bangumi for
    anime libraries (TMDb fallback), TMDb for everything else; emits
    'no_match' rows so we don't retry forever; AnyEnabled() for the
    scanner kick.
  - service/scanner.go: writes season/episode numbers for tv/anime libs
    and reports a 'probed' counter alongside 'added'.
  - service/transcoder.go (existing): unchanged, stays per-media.
  - service/subtitle.go: discovers external subtitles next to the source
    file (.srt/.vtt/.ass/.ssa) and converts SRT/ASS to WebVTT on the fly.
  - service/qbittorrent.go: thread-safe qBittorrent v2 Web UI client
    (login / add / list / delete) with cookie-jar reuse.
  - service/downloads.go: persists download tasks, reads runtime
    qbittorrent.* settings, polls /torrents/info every 5 s and pushes
    the result to WS subscribers ('download' topic).
  - service/subscription.go: 10-minute RSS poller with regex filter,
    GUID dedup persisted in the settings table, and 'subscription' WS
    events on enqueue.
  - service/watcher.go: fsnotify watcher with 5 s coalescing debouncer
    that triggers per-library rescans on create/rename/remove.
  - service/stats.go: dashboard snapshot — totals, recently added,
    gopsutil-driven CPU/mem/disk readings.
  - service/profile.go: non-credential profile patch + admin role mutator.
  - service/audit.go: best-effort writer for the access_logs table.
  - service/service.go: container wires every new service; Boot() spins
    up watcher / downloads poller / subscription scheduler; Close()
    tears them down on graceful shutdown.

Handlers
  - new files: downloads.go, subscriptions.go, subtitles.go, series.go,
    stats.go, profile.go, util.go.
  - handler.go: registers PATCH /me, /libraries/:id/seasons,
    /media/:id/subtitles, /subtitles/:id, /downloads*, /subscriptions*,
    /stats, /admin/users/:id/role.
  - auth.go / media.go: write audit rows for login + library CRUD and
    refresh the watcher when libraries change.

Frontend
  - api: new helpers for downloads, subscriptions, profile, series, stats,
    subtitles; library helper gained scrape().
  - hooks/useWebSocket.ts: shared connection with 3 s reconnect.
  - components/GlobalEvents.tsx: surfaces scan / scrape / subscription
    completion as toasts (mounted at app root).
  - pages: Library now switches to a season-grouped layout for tv/anime
    libraries; Player attaches WebVTT <track> elements; new pages for
    Downloads (live torrent table), Subscriptions, Profile, Stats.
  - components/Layout.tsx + App.tsx: sidebar groups (媒体库 / 自动化 /
    账号 / 管理) and routes for the new pages; /stats and /admin remain
    admin-only.
  - types/index.ts: new types — Subscription, DownloadTask, QBitTorrent,
    Hardware, StatsSnapshot.

Verified: go build, go vet, go test (incl. ParseEpisode + srtToVTT +
stripASSTags) all pass; tsc -b && vite build emits 17 route chunks plus
the deferred hls chunk; main bundle 247 KB / 83 KB gzipped.

web/src/App.tsx

@@ -30,6 +30,16 @@ const PlayerPage = lazy(() =>
   import('./pages/PlayerPage').then((m) => ({ default: m.PlayerPage })),
 )
 const AdminPage = lazy(() => import('./pages/AdminPage').then((m) => ({ default: m.AdminPage })))
+const DownloadsPage = lazy(() =>
+  import('./pages/DownloadsPage').then((m) => ({ default: m.DownloadsPage })),
+)
+const SubscriptionsPage = lazy(() =>
+  import('./pages/SubscriptionsPage').then((m) => ({ default: m.SubscriptionsPage })),
+)
+const ProfilePage = lazy(() =>
+  import('./pages/ProfilePage').then((m) => ({ default: m.ProfilePage })),
+)
+const StatsPage = lazy(() => import('./pages/StatsPage').then((m) => ({ default: m.StatsPage })))
 
 // Fallback shown while a chunk is loading.
 const Loading = () => <p className="px-6 py-8 text-slate-500">加载中…</p>
@@ -55,6 +65,17 @@ export default function App() {
           <Route path="playlist/:id" element={<PlaylistDetailPage />} />
           <Route path="media/:id" element={<MediaDetailPage />} />
           <Route path="play/:id" element={<PlayerPage />} />
+          <Route path="downloads" element={<DownloadsPage />} />
+          <Route path="subscriptions" element={<SubscriptionsPage />} />
+          <Route path="profile" element={<ProfilePage />} />
+          <Route
+            path="stats"
+            element={
+              <RequireAdmin>
+                <StatsPage />
+              </RequireAdmin>
+            }
+          />
           <Route
             path="admin"
             element={