Add movie/series ratings and watchlist

Builds on the accounts foundation: PUT/DELETE a rating (0.5-10.0) or a
watchlist entry on any movie or series, all scoped to the bearer token's
own user, plus GET /account/ratings|watchlist/{movies,series} to list
them back. Both are polymorphic entity_type/entity_id tables, same shape
as watch_provider_offerings and trending_entries, so movie and series
share one repository/router each rather than duplicating per type.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

app/models/__init__.py

@@ -24,6 +24,7 @@ from app.models.movie import (
 )
 from app.models.person import Person
 from app.models.provider import IngestionJob, Provider, ProviderRecord
+from app.models.rating import Rating
 from app.models.trending import TrendingEntry
 from app.models.tv import (
     Episode,
@@ -36,6 +37,7 @@ from app.models.tv import (
 from app.models.user import User
 from app.models.video import Video
 from app.models.watch_provider import WatchProvider, WatchProviderOffering
+from app.models.watchlist import WatchlistEntry
 
 __all__ = [
     "Base",
@@ -79,4 +81,6 @@ __all__ = [
     "WatchProviderOffering",
     "TrendingEntry",
     "User",
+    "Rating",
+    "WatchlistEntry",
 ]