feat: Flexion 先验签后消费支付流程 + playerId 绑定

实现 Flexion 渠道支付验签重构：支付成功后不立即消费，将 purchaseJson/signature/purchaseToken
回调至 Unity，由服务端 SHA1withRSA 验签并校验 developerPayload.playerId 后再调用 consume。
同步更新 SDKManager 接口、UnityBridgeFunc 桥接、TYSdkModel 字段及 ExtraPluginCfgs。

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

ExtraPluginCfgs/Android/flexion/ChannelHelpers.java

@@ -5,7 +5,7 @@ public class ChannelHelpers {
     public static final String CHANNEL = "Flexion";
 
     static void register() {
-        SDKManager.registerHelper(CHANNEL, new FlexionSDKHelper());
+        SDKManager.registerHelper(new FlexionSDKHelper());
     }
 
 
@@ -14,4 +14,7 @@ public class ChannelHelpers {
     public static String normalizeSkuList(String msg) {
         return msg;
     }
+    
+    
+    //public SDKExtBuilder;
 }