feat: implement useUrlState hook for managing URL-based state in admin pages

- Refactor multiple admin pages (BlogsPage, ClinicsPage, DoctorsPage, etc.) to utilize the new useUrlState hook for managing pagination, search, and filter states via URL.
- Ensure that the state persists in the URL, allowing users to return to the same state when navigating back from detail pages.
- Update relevant components to handle state changes appropriately and maintain clean URLs by removing default values.
- Add SlotPicker component for selecting appointment slots based on availability.
- Create tests for useUrlState to validate its functionality and ensure correct behavior when interacting with the URL.
- Update API documentation to reflect changes in appointment creation and slot selection processes.

assets/admin/pages/RepresentationsPage.tsx

@@ -7,6 +7,7 @@ import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';
 import { toast } from 'sonner';
 import { api } from '../lib/api';
+import { useUrlState, pageOf } from '../hooks/useUrlState';
 import type { ApiResponse, PaginatedResponse } from '../lib/api';
 import MobileInput from '../components/ui/MobileInput';
 import { iranMobileSchema } from '../lib/utils';
@@ -33,9 +34,14 @@ type FormData = z.infer<typeof schema>;
 export default function RepresentationsPage() {
   const navigate = useNavigate();
   const qc = useQueryClient();
-  const [page, setPage] = useState(1);
-  const [search, setSearch] = useState('');
-  const [cityFilter, setCityFilter] = useState<number | null>(null);
+  // وضعیت لیست در URL می‌ماند تا «بازگشت» از صفحهٔ جزئیات، همین فیلترها و صفحه را برگرداند.
+  const [urlState, setUrlState] = useUrlState({ page: '1', search: '', city: '' });
+  const page = pageOf(urlState.page);
+  const search = urlState.search;
+  const cityFilter = urlState.city === '' ? null : Number(urlState.city);
+  const setPage = (p: number) => setUrlState({ page: String(p) });
+  const setSearch = (v: string) => setUrlState({ search: v, page: '1' });
+  const setCityFilter = (v: number | null) => setUrlState({ city: v === null ? '' : String(v), page: '1' });
   const [addOpen, setAddOpen] = useState(false);
   const [deleteTarget, setDeleteTarget] = useState<Representation | null>(null);
   const limit = 15;