feat(settings): render doctor/clinic settings pages inside the settings shell

Wrap the existing settings-area pages — doctor profile (مدیریت پزشک),
insurance pricing (بیمه), payment report (پرداخت), SMS wallet (پیامک‌ها),
secretaries (منشی) and clinic info (مطب) — in SettingsLayout so they appear
under the settings sub-navigation like the Figma design, with the matching
menu item highlighted. Wire the doctor/clinic menu entries to their routes.

The نوبت‌دهی / برچسب‌ها / حساب کاربری entries stay as disabled placeholders
until they have their own pages/designs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

assets/admin/pages/SettingsMenuPage.test.tsx

@@ -17,6 +17,6 @@ describe('SettingsMenuPage', () => {
     // implemented → anchor with href
     expect(screen.getByText('خرید اشتراک').closest('a')).toHaveAttribute('href', '/admin/subscription');
     // not implemented → disabled button
-    expect(screen.getByText('مدیریت پزشک').closest('button')).toBeDisabled();
+    expect(screen.getByText('مدیریت نوبت دهی').closest('button')).toBeDisabled();
   });
 });