Add artwork self-hosting: local-disk download worker + storage

Section 10: every image API responses reference has pointed straight
at TMDb's CDN since day one -- Aurora never actually downloaded or
served artwork itself, despite storing dimensions/checksum/local_path
columns for exactly that. Closes the gap:

- is_primary was declared on the Artwork model but never actually set
  anywhere -- every row defaulted to False. Now the normalizer marks
  the one image each provider designates as *the* image for an entity
  (TMDb's poster_path/backdrop_path/profile_path) as primary,
  distinct from the dozens of alternates also ingested, including
  correctly marking an existing row primary (not inserting a
  duplicate) when that image already appears in the alternates list.
- app/services/artwork/: an ArtworkStorage interface with a
  LocalDiskStorage implementation (checksum-named files, single-host
  deployment via a Docker volume shared between api and worker -- see
  docs/architecture.md for the S3/R2 upgrade path), and a download
  pipeline with content-type validation, a size cap, and path-traversal
  protection.
- After movie/series/person ingestion succeeds, tasks.py cascades one
  download_artwork_task per primary artwork id via arq's ctx['redis']
  (same fan-out pattern as the season cascade) -- fire-and-forget, not
  tracked in ingestion_jobs, since a failed image cache is a
  known-safe fallback to the provider URL, not a user-facing failure.
- app/main.py serves MEDIA_ROOT at MEDIA_URL_PREFIX; local_path is
  preferred over original_url once set (already-existing fallback
  logic in app/services/common.py:artwork_url, now actually exercised).

Also fixes a real interaction bug this surfaced: every ingestion
pipeline deleted and recreated all of an entity's Artwork rows on each
re-sync, which would have silently wiped local_path/checksum on every
re-ingestion, forcing a full re-download every time and defeating the
point of caching locally at all. app/repositories/polymorphic.py's new
sync_artwork upserts by provider_asset_id (TMDb's stable per-image
path) instead, preserving downloaded copies across re-sync, and
replaces three near-identical delete+recreate helpers that used to
live separately in movie_ingestion.py, series_ingestion.py, and
person_ingestion.py.

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

app/services/ingestion/movie_ingestion.py

@@ -20,15 +20,15 @@ from sqlalchemy import delete
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.logging import get_logger
-from app.models.artwork import Artwork
 from app.models.company import MovieCompany
 from app.models.credit import Credit
-from app.models.enums import ArtworkType, MatchConfidence, MovieStatus, VideoType
+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.video import Video
 from app.providers.base import MetadataProvider
+from app.repositories import polymorphic
 from app.repositories import reference_repository as refs
 from app.repositories.provider_repository import get_or_create_provider, upsert_provider_record
 from app.services.metadata.matcher import match_entity
@@ -115,36 +115,9 @@ async def _replace_movie_credits(
         )
 
 
-_ARTWORK_TYPES = {t.value for t in ArtworkType}
 _VIDEO_TYPES = {t.value for t in VideoType}
 
 
-async def _replace_movie_artwork(
-    session: AsyncSession, movie_id: uuid.UUID, provider_id: uuid.UUID, artwork_list
-) -> None:
-    await session.execute(
-        delete(Artwork).where(Artwork.entity_type == "movie", Artwork.entity_id == movie_id)
-    )
-    for art in artwork_list:
-        art_type = art.artwork_type if art.artwork_type in _ARTWORK_TYPES else "poster"
-        session.add(
-            Artwork(
-                entity_type="movie",
-                entity_id=movie_id,
-                artwork_type=ArtworkType(art_type),
-                language_code=None,
-                width=art.width,
-                height=art.height,
-                aspect_ratio=art.aspect_ratio,
-                provider_id=provider_id,
-                provider_asset_id=art.provider_asset_id,
-                original_url=art.url,
-                vote_average=art.vote_average,
-                is_primary=False,
-            )
-        )
-
-
 async def _replace_movie_videos(
     session: AsyncSession, movie_id: uuid.UUID, provider_id: uuid.UUID, videos
 ) -> None:
@@ -259,7 +232,13 @@ async def ingest_movie(
     await _replace_movie_keywords(session, movie.id, normalized.keywords)
     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 _replace_movie_artwork(session, movie.id, tmdb_provider.id, normalized.artwork)
+    await polymorphic.sync_artwork(
+        session,
+        entity_type="movie",
+        entity_id=movie.id,
+        provider_id=tmdb_provider.id,
+        artwork_list=normalized.artwork,
+    )
     await _replace_movie_videos(session, movie.id, tmdb_provider.id, normalized.videos)
     await _link_external_ids(session, movie.id, tmdb_provider.id, normalized)