feat: enhance DoctorFormPage with searchable specialties and improved UI components

- Refactored DoctorFormPage to use Controller from react-hook-form for better form handling.
- Added a new Field component for consistent input styling and error handling.
- Implemented a SpecialtyPicker component with improved selection logic for specialties.
- Updated the layout and styling of the form sections for better user experience.
- Integrated SearchableSelect for selecting specialties and roles in DoctorsPage and UsersPage.
- Added createClinic API endpoint to handle clinic creation with validation for mobile and name fields.

assets/admin/pages/DoctorsPage.tsx

@@ -12,6 +12,7 @@ import type { ApiResponse, PaginatedResponse } from '../lib/api';
 import { formatDate, formatNumber } from '../lib/utils';
 import ConfirmDialog from '../components/ui/ConfirmDialog';
 import Pagination from '../components/ui/Pagination';
+import SearchableSelect from '../components/ui/SearchableSelect';
 
 // ── Types ─────────────────────────────────────────────────────────────────
 
@@ -227,13 +228,15 @@ export default function DoctorsPage() {
               />
             </div>
             {specialties.length > 0 && (
-              <div className="field">
-                <select value={specialtyId} onChange={(e) => setSpecialty(e.target.value)}>
-                  <option value="">همه تخصص‌ها</option>
-                  {specialties.map((s) => (
-                    <option key={s.id} value={String(s.id)}>{s.name}</option>
-                  ))}
-                </select>
+              <div style={{ minWidth: 180 }}>
+                <SearchableSelect
+                  options={specialties.map(s => ({ value: String(s.id), label: s.name }))}
+                  value={specialtyId || null}
+                  onChange={(v) => setSpecialty(v ? String(v) : '')}
+                  placeholder="همه تخصص‌ها"
+                  isClearable
+                  height={36}
+                />
               </div>
             )}
             <div className="seg">