Add payment methods management page

List Stripe payment methods with set-default and remove actions. Includes
delete confirmation dialog, breadcrumb navigation, and sidebar nav entry.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

website/app/Http/Controllers/Account/BillingController.php

@@ -76,6 +76,35 @@ class BillingController extends Controller
         return back()->with('success', 'Default payment method updated.');
     }
 
+    public function paymentMethods(Request $request): Response
+    {
+        $user = $request->user();
+        $paymentMethods = [];
+        $defaultPaymentMethod = null;
+
+        if ($user->hasStripeId()) {
+            $methods = $user->paymentMethods();
+            $defaultPm = $user->defaultPaymentMethod();
+            $defaultPaymentMethod = $defaultPm?->id;
+
+            foreach ($methods as $method) {
+                $paymentMethods[] = [
+                    'id' => $method->id,
+                    'brand' => $method->card->brand ?? 'unknown',
+                    'last_four' => $method->card->last_four ?? '****',
+                    'exp_month' => $method->card->exp_month,
+                    'exp_year' => $method->card->exp_year,
+                    'is_default' => $method->id === $defaultPaymentMethod,
+                ];
+            }
+        }
+
+        return Inertia::render('Billing/PaymentMethods', [
+            'paymentMethods' => $paymentMethods,
+            'defaultPaymentMethod' => $defaultPaymentMethod,
+        ]);
+    }
+
     public function invoices(Request $request): Response
     {
         $invoices = $request->user()