8e0d73c37e
- Add last_edited_at + last_edited_by columns to holidays + leave_records - Migration: ALTER TABLE adds columns (idempotent) - PUT endpoints set last_edited_at on every manual edit - POST /api/leave/upload: skip if last_edited_at NOT NULL, update otherwise - New POST /api/holidays/upload: same logic, admin only - LeaveOut + HolidayOut schemas include last_edited_at - Response includes added/updated/skipped counters - Verified: edited Jay Lam SL preserved, not-edited May Chan SL updated