Add collection/franchise ingestion

Collections were bare stubs (name only) lazily created the moment a
movie's belongs_to_collection reference was seen. Adds a real
ingest_collection pipeline: TMDb's /collection/{id} for overview and
poster/backdrop artwork, plus ordered CollectionMovie membership --
linking only movies already ingested into Aurora, the same
never-fabricate-a-stub rule movie recommendations already follow.

get_or_create_collection now refreshes name/overview on an existing
stub instead of only creating, guarded so a bare movie-stub call
(overview=None) never clobbers real data a full ingestion already
filled in.

New POST /api/v1/admin/ingest/collection endpoint and
ingest_collection_task; GET /api/v1/collections/{id} needed no changes
since its read path (collection_service.py) already assembled the full
detail shape.

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

app/services/ingestion/runner.py

@@ -33,6 +33,7 @@ from app.repositories.provider_repository import (
 )
 from app.repositories.tv_repository import get_seasons_for_series, get_series_companies
 from app.services.cache import build_key, cache_delete
+from app.services.ingestion.collection_ingestion import ingest_collection
 from app.services.ingestion.movie_ingestion import ingest_movie
 from app.services.ingestion.person_ingestion import ingest_person
 from app.services.ingestion.series_ingestion import ingest_season, ingest_series
@@ -164,6 +165,16 @@ async def run_series_ingestion(job_id: uuid.UUID, external_id: str) -> uuid.UUID
     )
 
 
+async def run_collection_ingestion(job_id: uuid.UUID, external_id: str) -> uuid.UUID:
+    return await _run_ingestion(
+        job_id,
+        "collection_ingestion",
+        lambda session, provider: ingest_collection(
+            session, provider, external_id, ingestion_job_id=job_id
+        ),
+    )
+
+
 async def run_season_ingestion(
     job_id: uuid.UUID, series_external_id: str, season_number: int
 ) -> uuid.UUID: