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>

ExtraPluginCfgs/Android/googleplay/ChannelHelpers.java

@@ -6,4 +6,8 @@ public class ChannelHelpers {
     static void register() {
         // GooglePlay uses default behavior, no additional SDKHelper
     }
+
+    public static String normalizeSkuList(String msg) {
+        return msg;
+    }
 }