feat: merge rustore test UI and unify SKU format across channels

- Merge VK login/link/check and Review test buttons from dev_rustore
- Unify Rustore/GooglePlay SKU format via ChannelHelpers.normalizeSkuList()
- Fix ChannelConfig runtime sync: Java InitSDK sets channel from ChannelHelpers.CHANNEL
- Fix AndroidMinSdkVersion 25→26 for tuyoosdk compatibility
- Fix Flexion AndroidManifest tools:replace missing fullBackupContent value
- Add [CHANNEL-VERIFY] debug logs for channel verification

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

sdk-intergration/Packages/tysdk/Runtime/UnityBridgeFunc.cs

@@ -66,6 +66,7 @@ namespace tysdk
                 using (var activityCls = new AndroidJavaClass("com.unity3d.player.UnityPlayer"))
                 {
                     var activity = activityCls.GetStatic<AndroidJavaObject>("currentActivity");
+                    UnityEngine.Debug.Log("[CHANNEL-VERIFY] C# InitSDK → ChannelConfig.Channel=" + ChannelConfig.Channel);
                     sdkManager.CallStatic("InitSDK", activity, ChannelConfig.Channel);
                 }
             }