docs: 添加 Unity Version Badge 到 README 头部

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

Author: AlianBlank

README.ja.md

@@ -6,6 +6,7 @@
 
 [![License](https://img.shields.io/github/license/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/blob/main/LICENSE.md)
 [![Version](https://img.shields.io/github/v/release/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/releases)
+[![Unity Version](https://img.shields.io/badge/Unity-2019.4-black?logo=unity)](https://unity.com/)
 [![Documentation](https://img.shields.io/badge/Documentation-docs-blue)](https://gameframex.doc.alianblank.com)
 
 インディゲーム開発者向けオールインワンソリューション · インディ開発者の夢を支援

README.ko.md

@@ -6,6 +6,7 @@
 
 [![License](https://img.shields.io/github/license/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/blob/main/LICENSE.md)
 [![Version](https://img.shields.io/github/v/release/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/releases)
+[![Unity Version](https://img.shields.io/badge/Unity-2019.4-black?logo=unity)](https://unity.com/)
 [![Documentation](https://img.shields.io/badge/Documentation-docs-blue)](https://gameframex.doc.alianblank.com)
 
 인디 게임 개발자를 위한 올인원 솔루션 · 인디 개발자의 꿈을 실현

README.md

@@ -6,6 +6,7 @@
 
 [![License](https://img.shields.io/github/license/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/blob/main/LICENSE.md)
 [![Version](https://img.shields.io/github/v/release/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/releases)
+[![Unity Version](https://img.shields.io/badge/Unity-2019.4-black?logo=unity)](https://unity.com/)
 [![Documentation](https://img.shields.io/badge/Documentation-docs-blue)](https://gameframex.doc.alianblank.com)
 
 All-in-One Solution for Indie Game Development · Empowering Indie Developers' Dreams

README.zh-CN.md

@@ -6,6 +6,7 @@
 
 [![License](https://img.shields.io/github/license/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/blob/main/LICENSE.md)
 [![Version](https://img.shields.io/github/v/release/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/releases)
+[![Unity Version](https://img.shields.io/badge/Unity-2019.4-black?logo=unity)](https://unity.com/)
 [![Documentation](https://img.shields.io/badge/Documentation-docs-blue)](https://gameframex.doc.alianblank.com)
 
 独立游戏前后端一体化解决方案 · 独立游戏开发者的圆梦大使

README.zh-TW.md

@@ -6,6 +6,7 @@
 
 [![License](https://img.shields.io/github/license/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/blob/main/LICENSE.md)
 [![Version](https://img.shields.io/github/v/release/GameFrameX/com.gameframex.unity.xincger.litjson)](https://github.com/GameFrameX/com.gameframex.unity.xincger.litjson/releases)
+[![Unity Version](https://img.shields.io/badge/Unity-2019.4-black?logo=unity)](https://unity.com/)
 [![Documentation](https://img.shields.io/badge/Documentation-docs-blue)](https://gameframex.doc.alianblank.com)
 
 獨立遊戲前後端一體化解決方案 · 獨立遊戲開發者的圓夢大使