048854f92a
Implements the stubbed /sync endpoints: - GET /sync/changes — delta pull (likes, plays, changed playlists with their track ids, changed catalogue tracks) over the half-open window (since, cursor]; the cursor is the DB clock, so it's immune to app/DB skew. - POST /sync/push — idempotent append of client like/play events (ON CONFLICT DO NOTHING by client-supplied id); events for tracks the server doesn't have are skipped (graceful degradation). Adds a server-ingestion column `synced_at` to the likes + play_history event logs (migration) as the delta ordering key, so an event pushed with an older event time still surfaces for other devices. Repos gain list_since/add_event (likes, history), list_changed_since (playlists, tracks) and playlist.track_ids; wired via SyncService in deps. Also fixes test isolation exposed by the registry-backed /admin/sources endpoint: test_sources_api clears the process-cached source registry, and test_admin_api no longer hardcodes the environment name. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>