Wires the persistence layer for CLIP semantic search. The watcher's
per-tick drain encodes any image_exif row with a known content_hash
but no clip_embedding via Apollo (cap CLIP_BACKLOG_MAX_PER_TICK,
default 32). On a query, /photos/search encodes the text via Apollo
and reranks every stored embedding in-memory.
ExifDao additions:
- list_clip_unencoded_candidates — partial-index scan for drain
- backfill_clip_embedding — touches only the two new columns
- list_clip_index — dedup'd (hash, embedding) pull for search
clip_watch::run_clip_encoding_pass is the parallel fan-out — tokio
runtime per pass with CLIP_ENCODE_CONCURRENCY (default 4). No marker
rows for permanent failures yet; per-tick cap bounds the retry cost.
/photos/search params: q, limit, threshold (default 0.20), library,
model_version. Response is intentionally minimal (path + score) so
the frontend joins against existing photo-metadata routes lazily.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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