feat(plex): Playlists Phase 1 — per-user ordered watch-lists (Siftlode-native)

Personal ordered lists of Plex items, kept in Siftlode's own DB (works for users
without a Plex account, like watch-state) — the "your own lists" counterpart to
shared collections. Plex-direction sync is a later phase (plex_rating_key
reserved).

Backend: migration 0048 (plex_playlists + plex_playlist_items with position),
PlexPlaylist/PlexPlaylistItem models, and per-user CRUD endpoints under
/api/plex/playlists (list [+?contains for the add dialog], create [seeded],
detail [ordered cards], rename, delete, add/remove item, reorder). _leaf_card
handles the movie/episode mix. Frontend: "Add to playlist" dialog from the movie
info page (all users), a Playlists section in PlexSidebar (list + create),
PlexPlaylistView (reorder up/down, remove, rename, delete, Play all), and
PlexPlayer gained an optional `queue` so play-through follows the list order
(prev/next + auto-advance). i18n en/hu/de. Verified end-to-end on localdev
(backend CRUD + the create→add→view→play-through UI flow).

frontend/src/lib/releaseNotes.ts

@@ -14,6 +14,15 @@ export interface ReleaseEntry {
 }
 
 export const RELEASE_NOTES: ReleaseEntry[] = [
+  {
+    version: "0.30.0",
+    date: "2026-07-06",
+    summary: "Plex playlists — your own ordered watch-lists.",
+    features: [
+      "Plex playlists: create your own ordered lists of films (each user has their own — no Plex account needed). Add a film to a playlist from its info page (\"Add to playlist\"), then find your playlists in the Plex sidebar.",
+      "Plex playlists: open a playlist to reorder (up/down), remove items, rename or delete it, and hit \"Play all\" to watch straight through — the player steps through the whole list in order, auto-advancing to the next.",
+    ],
+  },
   {
     version: "0.29.0",
     date: "2026-07-06",