Add watch providers (where to stream/rent/buy)

New TMDb integration end to end: append_to_response "watch/providers",
normalizer parsing grouped by country/monetization type, a WatchProvider
catalog entry (external-id keyed, same get_or_create pattern as Company/
Collection/Person) + polymorphic WatchProviderOffering table (new
migration 0002), ingestion write (including provider logos via the
existing Artwork table), and API exposure -- embedded on movie/series
detail plus a dedicated /watch-providers sub-route, shaped to mirror
TMDb's own response for easy porting.

Note: this data comes from JustWatch via TMDb and carries its own
attribution requirement separate from TMDb's general one -- flagged in
docs/api.md, must be satisfied before showing this in the frontend.

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

app/api/v1/series.py

@@ -19,6 +19,7 @@ from app.schemas.tv import (
     SeriesListOut,
     SeriesSeasonsOut,
     SeriesVideosOut,
+    SeriesWatchProvidersOut,
 )
 from app.services import tv_service
 from app.services.cache import build_key
@@ -109,3 +110,13 @@ async def get_series_videos(
         return await tv_service.get_series_videos(session, aurora_id)
     except tv_service.SeriesNotFoundError as exc:
         raise not_found("series", aurora_id) from exc
+
+
+@router.get("/{aurora_id}/watch-providers", response_model=SeriesWatchProvidersOut)
+async def get_series_watch_providers(
+    aurora_id: str, session: AsyncSession = Depends(get_db)
+) -> SeriesWatchProvidersOut:
+    try:
+        return await tv_service.get_series_watch_providers(session, aurora_id)
+    except tv_service.SeriesNotFoundError as exc:
+        raise not_found("series", aurora_id) from exc