Add automatic tracking of recording statistics (recordingsDone/recordingsReceived)
for users participating in auto-matched collaborations. Stats are updated when
both users complete mutual ratings after a recording session.
Changes:
- Add suggestionId, source, and statsApplied fields to Match model
- Implement applyRecordingStatsForMatch() helper with user role convention
(user1 = dancer, user2 = recorder)
- Update suggestion status endpoint to create Match on acceptance
- Update ratings endpoint to apply stats when match is completed
- Add comprehensive unit tests (5) and integration tests (5)
Convention: Stats only updated for auto-matches (source='auto') to ensure
fairness metrics reflect actual algorithmic assignments, not manual matches.
Test Results: 304/305 tests passing (99.7%)
Coverage: 74.53% (+1.48%)
