feat(backup): add database backup/restore with scheduled retention and admin dashboard

- Add BackupRecord model for tracking backup archives
- Add migration 021_add_backup_records
- Add backup configuration settings (backup_enabled, backup_dir, backup_remote_destination, backup_remote_folder, backup_retain_hourly/daily/weekly)
- Add backup_tasks.py with create_backup, cleanup_old_backups, and helpers
- Register hourly/daily/weekly Celery beat schedules
- Add /api/admin/backup/* REST endpoints (list, create, download, restore, delete, cleanup)
- Add /admin/backup dashboard view and template
- Add backup link to admin dropdown navigation in base.html
- Add backup settings to SETTING_METADATA in settings_service.py
- Add comprehensive test suite (39 tests passing)

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/api/__init__.py

@@ -8,6 +8,7 @@ from fastapi import APIRouter
 
 from app.api.admin_users import router as admin_users_router
 from app.api.azure import router as azure_router
+from app.api.backup import router as backup_router
 from app.api.billing import router as billing_router
 from app.api.database import router as database_router
 from app.api.diagnostic import router as diagnostic_router
@@ -43,6 +44,7 @@ router = APIRouter()
 # Include all the routers
 router.include_router(admin_users_router)
 router.include_router(user_router)
+router.include_router(backup_router)
 router.include_router(files_router)
 router.include_router(process_router)
 router.include_router(diagnostic_router)