C-01: Replace setattr loop with explicit field assignment in update_profile
C-02: Fix useEffect dependency to profileQuery.dataUpdatedAt for re-sync
W-01: Add audit log entry for profile updates
W-02: Use less misleading generic error for email uniqueness on registration
W-03: Early return on empty PUT body to avoid unnecessary commit
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>