- video_database: owned_movie_tmdb_ids (diff set), owned_movie_collections (franchises you've
started, most-invested first), top_owned_people (directors/creators you own the most).
- engine.collection(id): cached + owned-annotated franchise film list (person_detail already
gives owned-annotated filmography).
- /api/video/discover/gaps: builds 'Complete the <franchise>' rails (collection_gaps) + 'More
from <person>' rails (filmography_gaps, movies, vote-filtered) — the 'what am I missing' section.
All additive; gap diffs are the pure tested core.
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