修复百家乐下注余额检查：gold→jjb，与UserCurrencyService字段映射一致

app/Http/Controllers/BaccaratController.php

@@ -98,8 +98,8 @@ class BaccaratController extends Controller
 
         $user = $request->user();
 
-        // 检查用户金币余额
-        if ($user->gold < $data['amount']) {
+        // 检查用户金币余额（金币字段为 jjb）
+        if (($user->jjb ?? 0) < $data['amount']) {
             return response()->json(['ok' => false, 'message' => '金币不足，无法下注。']);
         }