2026.08.04-admin-schedule-priority
- Added field-level administrator ownership for exam start and end times.
- Admin-entered or admin-changed schedule values override teacher edits.
- Blank admin schedule fields remain delegated to the teacher.
- Added server-side enforcement and teacher UI read-only indicators.
- Prevented teacher Publish/Reopen from clearing an administrator-controlled expired schedule.
- Preserved Asia/Riyadh and MySQL UTC+03:00 handling.
