refactor: 支付链路规范化 — 统一命名/层次/传参

- ISDKHelper.pay() 增加 productPrice 参数，与 UnityKnowNew 签名对齐
- FlexionSDKHelper: prodPrice/prodCount 从参数直接写入 developerPayload
- playerId → userId 统一命名 (SDKTest/Java payload)
- pfId → pfid 统一小写 (服务端 JSON key)
- PaymentInfo 序列化替代 StringBuilder 手拼 JSON
- FlexionPaymentVerifier.Consume 走 UnityBridgeFunc.ConsumePurchase 桥接层
- UnityBridgeFunc 新增 ConsumePurchase 通用方法，移除渠道特定方法
- SDKManager.ConsumeFlexionPurchase → ConsumePurchase 通用化

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

sdk-intergration/Assets/Scripts/SDKTest.cs

@@ -231,7 +231,7 @@ public class SDKTest : MonoBehaviour
         var purchaseInfo = new JObject();
         purchaseInfo["pfid"] = "TestPlayer";
         purchaseInfo["customData"] =  "{\"test\":\"test\"}";
-        purchaseInfo["playerId"] = TYSdkFacade.TYAccountInfo.strUserId;
+        purchaseInfo["userId"] = TYSdkFacade.TYAccountInfo.strUserId;
 
         PaymentInfo payResult = await TYSdkFacade.Instance.Pay(sku, 1, sku.ProdPrice, purchaseInfo);
         _messageTxt.text = "\n" + $"Success : {payResult.isSuccess}";