fix(admin): pagination, patch tests, and per-page limits

Backend:
- Fix GetAllAdminBookingsHandler and SearchAdminBookingsHandler to
  return totalPages in response
- Auto-record patch tests when booking status progresses to "completed"
- Add GET/POST /api/admin/users/{id}/patch-tests endpoints
  Frontend:
- BookingsCard: proper pagination with 4 per page, prev/next buttons
- UsersCard, BookingCreateModal, WalkInCreateModal: per_page=4 for user
  search
- Add PatchTestModal for manual patch test entry in UserModal
- Hide patch test section when user has no eligible services
  Database:
- Add UNIQUE constraint on user_service_patch_tests(user_id, service_id)

frontend/src/lib/components/admin/UsersCard.svelte

@@ -41,7 +41,7 @@
 		try {
 			const params = new URLSearchParams({
 				page: page.toString(),
-				per_page: '10'
+				per_page: '4'
 			});
 
 			if (search.trim()) {