feat(admin): 仪表盘 KPI 聚焦收费主链（套餐/订阅/平台订单）

app/Http/Controllers/Admin/DashboardController.php

@@ -10,6 +10,7 @@ use App\Models\Product;
 use App\Models\Merchant;
 use App\Models\Plan;
 use App\Models\PlatformOrder;
+use App\Models\SiteSubscription;
 use App\Models\User;
 use App\Support\CacheKeys;
 use Illuminate\Http\Request;
@@ -35,6 +36,8 @@ class DashboardController extends Controller
                 'orders' => Order::count(),
 
                 // 收费中心（平台侧）
+                'plans' => Plan::count(),
+                'site_subscriptions' => SiteSubscription::count(),
                 'platform_orders' => PlatformOrder::count(),
                 'platform_orders_unpaid_pending' => PlatformOrder::query()
                     ->where('payment_status', 'unpaid')