Complete back button logic for all admin pages in Telegram Mini App

Main sections navigate to /admin (15 pages)
Detail/edit pages navigate to parent lists (16 pages)
All pages use useBackButton hook with proper navigation paths
Native Telegram back button in Mini App, UI button on web
Email template pages keep UI-only back buttons as required

src/pages/AdminPromocodeCreate.tsx

@@ -10,9 +10,22 @@ import {
   PromoCodeUpdateRequest,
   PromoGroup,
 } from '../api/promocodes';
-import { AdminBackButton } from '../components/admin';
+import { useBackButton } from '../platform/hooks/useBackButton';
+import { usePlatform } from '../platform/hooks/usePlatform';
 
 // Icons
+const BackIcon = () => (
+  <svg
+    className="h-5 w-5 text-dark-400"
+    fill="none"
+    viewBox="0 0 24 24"
+    stroke="currentColor"
+    strokeWidth={2}
+  >
+    <path strokeLinecap="round" strokeLinejoin="round" d="M15.75 19.5L8.25 12l7.5-7.5" />
+  </svg>
+);
+
 const RefreshIcon = () => (
   <svg
     className="h-4 w-4 animate-spin"
@@ -34,8 +47,12 @@ export default function AdminPromocodeCreate() {
   const navigate = useNavigate();
   const { id } = useParams<{ id: string }>();
   const queryClient = useQueryClient();
+  const { capabilities } = usePlatform();
   const isEdit = !!id;
 
+  // Use native Telegram back button in Mini App
+  useBackButton(() => navigate('/admin/promocodes'));
+
   // Form state
   const [code, setCode] = useState('');
   const [type, setType] = useState<PromoCodeType>('balance');
@@ -186,7 +203,15 @@ export default function AdminPromocodeCreate() {
     <div className="space-y-6">
       {/* Header */}
       <div className="flex items-center gap-3">
-        <AdminBackButton to="/admin/promocodes" />
+        {/* Show back button only on web, not in Telegram Mini App */}
+        {!capabilities.hasBackButton && (
+          <button
+            onClick={() => navigate('/admin/promocodes')}
+            className="flex h-10 w-10 items-center justify-center rounded-xl border border-dark-700 bg-dark-800 transition-colors hover:border-dark-600"
+          >
+            <BackIcon />
+          </button>
+        )}
         <div>
           <h1 className="text-xl font-bold text-dark-100">
             {isEdit