feat: bump version to 2.3.1

- Update versionName to 2.3.1
- Update versionCode to 231
- Test ReTrace mapping file upload with minification

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: graycreate

config.gradle

@@ -1,7 +1,7 @@
 ext {
     app = [
-            versionCode: 230,
-            versionName: "2.3.0"
+            versionCode: 231,
+            versionName: "2.3.1"
     ]
     android = [
             supportVersion: '26.1.0'