Add keyword browsing/filtering and expose alternate titles

Keywords were ingested and shown read-only on detail pages, but had no
directory (GET /keywords) or filter param -- the same gap genres had
before today. Mirrors the genre browse pattern exactly: repository,
service, route, plus a `keyword` filter on GET /movies and GET /series.

Alternate/translated titles ("Also Known As") were normalized down to
bare title strings and never written to MovieAlternateTitle/
SeriesAlternateTitle at all. Normalizer now captures country_code + type
per TMDb's actual shape; ingestion writes them; movie/series detail now
expose an alternate_titles list.

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

app/services/ingestion/movie_ingestion.py

@@ -25,7 +25,7 @@ from app.models.credit import Credit
 from app.models.enums import MatchConfidence, MovieStatus, VideoType
 from app.models.genre import MovieGenre
 from app.models.keyword import MovieKeyword
-from app.models.movie import Movie, MovieRecommendation
+from app.models.movie import Movie, MovieAlternateTitle, MovieRecommendation
 from app.models.video import Video
 from app.providers.base import MetadataProvider
 from app.repositories import polymorphic
@@ -51,6 +51,24 @@ async def _replace_movie_keywords(session: AsyncSession, movie_id: uuid.UUID, na
         session.add(MovieKeyword(movie_id=movie_id, keyword_id=keyword.id))
 
 
+async def _replace_movie_alternate_titles(
+    session: AsyncSession, movie_id: uuid.UUID, alt_titles
+) -> None:
+    await session.execute(
+        delete(MovieAlternateTitle).where(MovieAlternateTitle.movie_id == movie_id)
+    )
+    for alt in alt_titles:
+        country_code = None
+        if alt.country_code:
+            country = await refs.get_or_create_country(session, alt.country_code, alt.country_code)
+            country_code = country.code
+        session.add(
+            MovieAlternateTitle(
+                movie_id=movie_id, title=alt.title, country_code=country_code, type=alt.type
+            )
+        )
+
+
 async def _replace_movie_companies(
     session: AsyncSession, movie_id: uuid.UUID, provider_id: uuid.UUID, companies
 ) -> None:
@@ -239,6 +257,7 @@ async def ingest_movie(
 
     await _replace_movie_genres(session, movie.id, normalized.genres)
     await _replace_movie_keywords(session, movie.id, normalized.keywords)
+    await _replace_movie_alternate_titles(session, movie.id, normalized.alternate_titles)
     await _replace_movie_companies(session, movie.id, tmdb_provider.id, normalized.companies)
     await _replace_movie_credits(session, movie.id, tmdb_provider.id, normalized.cast, normalized.crew)
     await polymorphic.sync_artwork(