Add watched series/authors feature

Introduce watched lists for series and authors end-to-end.

- Add DB migration to create watched_series and watched_authors tables with indexes and foreign keys.
- Implement API routes: GET/POST for listing/adding and DELETE by id for both /api/user/watched-series and /api/user/watched-authors. Validation, ownership checks, and immediate targeted job triggers are included.
- Add client hooks (useWatchedSeries, useWatchedAuthors) with add/delete helpers and SWR revalidation.
- Add UI components: WatchButton (toggle/confirm) and WatchedListsSection for profile display and removal UX.
- Add processor (check-watched-lists.processor) and service (watched-lists.service) to scrape Audible, deduplicate, check library ownership, and auto-create requests; supports targeted checks for newly watched items.
- Include tests for the watched-lists service.

These changes implement the watched-lists feature to let users watch series/authors and have the system automatically detect and request new releases.

src/app/profile/page.tsx

@@ -12,6 +12,7 @@ import { useAuth } from '@/contexts/AuthContext';
 import { useRequests } from '@/lib/hooks/useRequests';
 import { cn } from '@/lib/utils/cn';
 import { GoodreadsShelvesSection } from '@/components/profile/GoodreadsShelvesSection';
+import { WatchedSeriesSection, WatchedAuthorsSection } from '@/components/profile/WatchedListsSection';
 
 const statConfig = [
   { key: 'total', label: 'Total', color: 'text-gray-900 dark:text-white' },
@@ -142,6 +143,12 @@ export default function ProfilePage() {
         {/* Goodreads Shelves */}
         <GoodreadsShelvesSection />
 
+        {/* Watched Series */}
+        <WatchedSeriesSection />
+
+        {/* Watched Authors */}
+        <WatchedAuthorsSection />
+
         {/* Active Downloads */}
         {activeDownloads.length > 0 && (
           <section>