Add GET /movies/{id}/recommendations

Ingestion already stored movie_recommendations edges from TMDb's
recommendations list (linking only to movies already ingested into
Aurora, per the never-fabricate-a-stub rule), but nothing exposed them.
Adds the repository lookup, service assembly, and route to read them
back in ranked order.

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

tests/integration/test_movie_ingestion.py

@@ -5,6 +5,7 @@ against PostgreSQL."""
 
 from __future__ import annotations
 
+import uuid
 from typing import Any
 
 import pytest
@@ -148,3 +149,38 @@ async def test_movie_detail_surfaces_company_logo_path(db_session: AsyncSession)
     roadshow = next(c for c in detail.companies if c.name == "Village Roadshow Pictures")
     assert roadshow.logo_path is not None
     assert roadshow.logo_path.endswith("/village-roadshow-logo.png")
+
+
+@pytest.mark.asyncio
+async def test_movie_recommendations_only_include_already_ingested_movies(
+    db_session: AsyncSession,
+):
+    """TMDb's recommendations list can reference movies Aurora hasn't
+    ingested yet; ingest_movie must link only the ones it can resolve by
+    external id (section 15: never fabricate a stub for an unseen entity),
+    and GET .../recommendations must return them in TMDb's ranked order."""
+
+    sequel_payload = {**FAKE_MOVIE, "id": 604, "title": "The Matrix Reloaded"}
+    await ingest_movie(db_session, FakeTMDbProvider(sequel_payload), "604")
+    await db_session.flush()
+
+    movie_with_recs = {
+        **FAKE_MOVIE,
+        "recommendations": {"results": [{"id": 604}, {"id": 999999}]},
+    }
+    movie_id = await ingest_movie(db_session, FakeTMDbProvider(movie_with_recs), "603")
+    await db_session.commit()
+
+    recs = await movie_service.get_movie_recommendations(
+        db_session, aurora_id("movie", str(movie_id))
+    )
+
+    assert [r.title for r in recs.recommendations] == ["The Matrix Reloaded"]
+
+
+@pytest.mark.asyncio
+async def test_movie_recommendations_not_found_for_unknown_movie(db_session: AsyncSession):
+    with pytest.raises(movie_service.MovieNotFoundError):
+        await movie_service.get_movie_recommendations(
+            db_session, aurora_id("movie", str(uuid.uuid4()))
+        )