refactor: standardize Inertia view paths and clean up controllers

- Pluralized view paths for consistency (Billing → Billings, Delivery → Deliveries, Order → Orders)

Author: RLASH18

app/Http/Controllers/Admin/BillingController.php

@@ -26,7 +26,7 @@ public function index(Request $request)
         $filters = $request->only(['search', 'status', 'payment_method']);
         $billings = $this->billingService->getAllPaginated(10, $filters);
 
-        return Inertia::render('admin/Billing/Index', [
+        return Inertia::render('admin/Billings/Index', [
             'billings' => $billings,
             'filters' => $filters,
         ]);
@@ -43,7 +43,7 @@ public function show(int $id)
             return $this->flashError('Billing not found', 'admin.billings.index');
         }
 
-        return Inertia::render('admin/Billing/Show', [
+        return Inertia::render('admin/Billings/Show', [
             'billing' => $billing
         ]);
     }

app/Http/Controllers/Admin/DeliveryController.php

@@ -27,7 +27,7 @@ public function index(Request $request)
         $filters = $request->only(['search', 'status']);
         $deliveries = $this->deliveryService->getAllPaginated(10, $filters);
 
-        return Inertia::render('admin/Delivery/Index', [
+        return Inertia::render('admin/Deliveries/Index', [
             'deliveries' => $deliveries,
             'filters' => $filters
         ]);
@@ -44,7 +44,7 @@ public function show(int $id)
             return $this->flashError('Delivery not found', 'admin.deliveries.index');
         }
 
-        return Inertia::render('admin/Delivery/Show', [
+        return Inertia::render('admin/Deliveries/Show', [
             'delivery' => $delivery
         ]);
     }

app/Http/Controllers/Admin/OrderController.php

@@ -33,7 +33,7 @@ public function index(Request $request)
 
         $orders = $this->orderService->getAllPaginated(10, $filters);
 
-        return Inertia::render('admin/Order/Index', [
+        return Inertia::render('admin/Orders/Index', [
             'orders' => $orders,
             'filters' => $filters,
         ]);
@@ -50,7 +50,7 @@ public function show(int $id)
             return $this->flashError('Order not found', 'admin.orders.index');
         }
 
-        return Inertia::render('admin/Order/Show', [
+        return Inertia::render('admin/Orders/Show', [
             'order' => $order,
         ]);
     }