Find & Add on the playlist-sync page only wrote sync_match_cache, which is
DELETEd wholesale after every DB scan — so the source->library pairing (and
the user's manual matches) reverted to 'extra'/red-dot on the next shallow
scan. The three match stores (sync_match_cache, manual_library_track_matches,
discovery extra_data) were disconnected and all pointed at tracks.id, which a
rescan re-keys (esp. Jellyfin/Navidrome GUIDs).
Unify the match so it's one durable fact, recorded once, honored everywhere:
- Find & Add also writes a durable manual_library_track_matches row (one-way;
the manual-match tool has no playlist to act on, so no reverse). Carries the
library file path.
- New library_file_path column (idempotent migration) + find_track_id_by_file_path:
re-resolve a stale library_track_id after a rescan re-keys the track, and
self-heal the row.
- The sync compare display's override lookup now falls back to the durable
manual match (resolve_durable_match_server_id) when sync_match_cache misses —
so the pairing persists across a scan instead of reverting to a red dot.
Purely additive: only adds matches when the cache returns nothing.
Tests: durable resolver (valid / stale-reresolve+self-heal / no-match / not-in-
playlist / missing-methods), file_path persistence + find_track_id_by_file_path.