Update README with migration notice

Added a migration notice to both English and Chinese README files, indicating the plugin is moving to libnativeapi/nativeapi-flutter for improved cross-platform native API support. Removed outdated migration notes and promotional content.

Author: lijy91

README-ZH.md

@@ -1,4 +1,6 @@
-> **🚀 快速发布您的应用**: 试试 [Fastforge](https://fastforge.dev) - 构建、打包和分发您的 Flutter 应用最简单的方式。
+> **⚠️ 迁移通知**: 本插件正在迁移到 [libnativeapi/nativeapi-flutter](https://github.com/libnativeapi/nativeapi-flutter)
+>
+> 新版本基于统一的 C++ 核心库（[libnativeapi/nativeapi](https://github.com/libnativeapi/nativeapi)），提供更完整、一致的跨平台原生 API 支持。
 
 # tray_manager
 
@@ -12,8 +14,6 @@
 
 这个插件允许 Flutter 桌面应用定义系统托盘。
 
-> 注意：本插件计划迁移至 [nativeapi](https://github.com/leanflutter/nativeapi-flutter) 以提升可维护性和性能，但目前该方案仍处于实验阶段。
-
 [English](./README.md) | 简体中文
 
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README.md

@@ -1,6 +1,7 @@
-> **🚀 Ship Your App Faster**: Try [Fastforge](https://fastforge.dev) - The simplest way to build, package and distribute your Flutter apps.
-
-# tray_manager
+> **⚠️ Migration Notice**: This plugin is being migrated to [libnativeapi/nativeapi-flutter](https://github.com/libnativeapi/nativeapi-flutter)
+>
+> The new version is based on a unified C++ core library ([libnativeapi/nativeapi](https://github.com/libnativeapi/nativeapi)), providing more complete and consistent cross-platform native API support.
+r
 
 [![pub version][pub-image]][pub-url] [![][discord-image]][discord-url] ![][visits-count-image]
 
@@ -12,8 +13,6 @@
 
 This plugin allows Flutter desktop apps to defines system tray.
 
-> Note: This plugin is planned to migrate to [nativeapi](https://github.com/leanflutter/nativeapi-flutter) to improve maintainability and performance, but the solution is still experimental at this stage.
-
 English | [简体中文](./README-ZH.md)
 
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