Fix two more test bugs surfaced by the full integration run

1. test_ingestion_cache_invalidation.py: the job was created through
   the test's db_session fixture, whose commit() only ends a savepoint
   that gets rolled back at teardown (see tests/conftest.py) -- it's
   never a real commit. _run_ingestion looks the job up through its
   own session_scope() (a genuinely separate connection), which could
   never see it, so the very first _require_job call raised "job
   vanished mid-run" every time. Worse, test_failed_ingestion_does_not_
   invalidate_the_cache still passed, coincidentally -- it expected a
   RuntimeError and got one, just the wrong one, masking the bug.
   Fixed by having _make_job create the job through session_scope()
   itself, matching test_ingestion_retry.py's existing pattern.

2. Same class of bug as the video-collision fix in the last commit:
   FAKE_MOVIE's fixed imdb_id ("tt0133093"), not just its video, also
   collides across two different fake movies sharing it unmodified --
   uq_external_id_source is a real unique constraint on
   (provider_id, entity_type, external_id). Fixed by also overriding
   imdb_id on the second movie in both affected tests.

All caught by running the actual integration suite against Postgres --
these paths were previously only collect-only'd locally (no local DB).

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

tests/integration/test_movie_ingestion.py

@@ -188,16 +188,17 @@ async def test_movie_recommendations_only_include_already_ingested_movies(
     external id (section 15: never fabricate a stub for an unseen entity),
     and GET .../recommendations must return them in TMDb's ranked order."""
 
-    # videos overridden to empty: FAKE_MOVIE's embedded video has a fixed
-    # provider_video_id, and two different movies both ingesting it would
-    # collide on the real uq_video_provider_source unique constraint --
-    # a video id is only ever attached to one entity, unlike genres/companies
-    # which are legitimately shared.
+    # videos and imdb_id overridden: FAKE_MOVIE's embedded video and imdb_id
+    # are both fixed identifiers, and two different movies both ingesting
+    # them unmodified would collide on the real uq_video_provider_source /
+    # uq_external_id_source unique constraints -- each belongs to exactly
+    # one entity, unlike genres/companies which are legitimately shared.
     sequel_payload = {
         **FAKE_MOVIE,
         "id": 604,
         "title": "The Matrix Reloaded",
         "videos": {"results": []},
+        "imdb_id": "tt0234215",
     }
     await ingest_movie(db_session, FakeTMDbProvider(sequel_payload), "604")
     await db_session.flush()