Surface series/episode credits in person filmography

/people/{id}/credits only ever looked at entity_type == "movie",
silently dropping the series-level cast/crew and episode-level
guest-star Credit rows that series_ingestion.py has been writing all
along -- a person ingested via a TV show would show an empty or
movie-only filmography no matter how much TV work was actually in the
database.

Regular series credits map straight to a filmography row, same shape
as movies. Guest-star episode credits are aggregated to one row per
(series, department/job/character) with an episode_count, rather than
one row per episode -- a prolific guest actor would otherwise flood
the list with dozens of near-identical entries. Added
tv_repository.get_series_by_ids/get_episodes_by_ids (bulk, mirroring
the existing movie_repository pattern) to support it.

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

app/schemas/person.py

@@ -28,6 +28,11 @@ class FilmographyCreditOut(BaseModel):
     character: str | None = None
     release_date: date | None = None
     poster_path: str | None = None
+    # Set only for series filmography built from guest-star episode credits:
+    # how many distinct episodes this character/credit appeared in, since
+    # those are aggregated to one row per series rather than one per
+    # episode. None for movie credits and regular (non-guest) series roles.
+    episode_count: int | None = None
 
 
 class PersonDetailOut(BaseModel):