Move payment method editing to separate page and fix auth error handling

- Replace modal with dedicated AdminPaymentMethodEdit page
- Add route /admin/payment-methods/:methodId/edit
- Fix 401 error handling for auth endpoints to show error messages instead of reloading page
- Update client.ts to use window.Telegram.WebApp.initData directly
- Maintain useTelegramDnd for drag and drop functionality

src/App.tsx

@@ -54,6 +54,7 @@ const AdminCampaignEdit = lazy(() => import('./pages/AdminCampaignEdit'));
 const AdminUsers = lazy(() => import('./pages/AdminUsers'));
 const AdminPayments = lazy(() => import('./pages/AdminPayments'));
 const AdminPaymentMethods = lazy(() => import('./pages/AdminPaymentMethods'));
+const AdminPaymentMethodEdit = lazy(() => import('./pages/AdminPaymentMethodEdit'));
 const AdminPromoOffers = lazy(() => import('./pages/AdminPromoOffers'));
 const AdminPromoOfferTemplateEdit = lazy(() => import('./pages/AdminPromoOfferTemplateEdit'));
 const AdminPromoOfferSend = lazy(() => import('./pages/AdminPromoOfferSend'));
@@ -531,6 +532,16 @@ function App() {
             </AdminRoute>
           }
         />
+        <Route
+          path="/admin/payment-methods/:methodId/edit"
+          element={
+            <AdminRoute>
+              <LazyPage>
+                <AdminPaymentMethodEdit />
+              </LazyPage>
+            </AdminRoute>
+          }
+        />
         <Route
           path="/admin/promo-offers"
           element={