Add /dashboard route, mark-all-watched on complete, keyboard fixes

- Move dashboard page to app/(pages)/dashboard, redirect / to /dashboard
  for authenticated users, update all nav/breadcrumb/auth hrefs
- Mark all episodes watched when a TV show status is set to "completed"
  (markAllEpisodesWatched skips already-watched episodes)
- Refactor KeyboardProvider to store shortcuts in a ref instead of
  state, eliminating unnecessary re-renders; use react-hotkeys-hook for
  Cmd+K so it works reliably in form inputs
- Fix useRegisterShortcut: re-register on every render (stable ref read)
  with a separate cleanup effect, removing brittle key memoization
- Search page: silently navigate to title detail on import instead of
  showing "Added to library" toast

package.json

@@ -29,6 +29,7 @@
     "react": "19.2.4",
     "react-day-picker": "^9.14.0",
     "react-dom": "19.2.4",
+    "react-hotkeys-hook": "^5.2.4",
     "react-resizable-panels": "^4.6.5",
     "recharts": "2.15.4",
     "shadcn": "^3.8.5",