feat(subscription): gate insurance pages behind "insurance" plan feature

Wrap InsurancePricingPage and ClaimsPage in <FeatureGate feature="insurance">
so direct-URL access is blocked without an active subscription that enables
the feature. Add feature: "insurance" to the sidebar links (doctor/clinic/
secretary sections) so the menu items hide when the plan lacks it.

Make AdminSubscriptionPage feature controls dynamic: derive the plan feature
checkboxes from FEATURE_LABELS (now including "insurance") and switch the Zod
schema to z.record, so adding a feature only touches the label map.

No backend/migration change: plan.features is free-form JSON; existing plans
default to insurance:false and admins enable it per plan.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/admin/pages/ClaimsPage.tsx

@@ -7,6 +7,7 @@ import { formatRial, formatNumber } from '../lib/utils';
 import PageHeader from '../components/ui/PageHeader';
 import Modal from '../components/ui/Modal';
 import SearchableSelect from '../components/ui/SearchableSelect';
+import FeatureGate from '../components/ui/FeatureGate';
 
 interface ClaimItem {
   invoice_item_id: number;
@@ -80,6 +81,7 @@ export default function ClaimsPage() {
   });
 
   return (
+    <FeatureGate feature="insurance">
     <div className="fade-in">
       <PageHeader title="مطالبات بیمه" description="پیگیری مطالبات و بدهی بیمه‌ها" />
 
@@ -189,5 +191,6 @@ export default function ClaimsPage() {
         </div>
       </Modal>
     </div>
+    </FeatureGate>
   );
 }