feat: 新增文件传输助手功能及相关组件

新增文件传输助手功能，包含设备发现、配对、传输等核心模块。主要变更包括：
1. 新增局域网、蓝牙、NFC等多种设备发现方式
2. 实现基于WebRTC、TCP、USB等多种传输协议
3. 添加相关权限管理及状态监控
4. 完善UI界面及交互流程
5. 更新依赖库及版本号至4.19.0

同时优化部分现有功能：
1. 聊天会话增加隐藏功能
2. 完善本地通知权限处理
3. 修复部分已知问题

windows/flutter/generated_plugin_registrant.cc

@@ -13,9 +13,11 @@
 #include <file_selector_windows/file_selector_windows.h>
 #include <flutter_inappwebview_windows/flutter_inappwebview_windows_plugin_c_api.h>
 #include <flutter_secure_storage_windows/flutter_secure_storage_windows_plugin.h>
+#include <flutter_webrtc/flutter_web_r_t_c_plugin.h>
 #include <gal/gal_plugin_c_api.h>
 #include <local_auth_windows/local_auth_plugin.h>
 #include <permission_handler_windows/permission_handler_windows_plugin.h>
+#include <record_windows/record_windows_plugin_c_api.h>
 #include <share_plus/share_plus_windows_plugin_c_api.h>
 #include <sqlite3_flutter_libs/sqlite3_flutter_libs_plugin.h>
 #include <url_launcher_windows/url_launcher_windows.h>
@@ -35,12 +37,16 @@ void RegisterPlugins(flutter::PluginRegistry* registry) {
       registry->GetRegistrarForPlugin("FlutterInappwebviewWindowsPluginCApi"));
   FlutterSecureStorageWindowsPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("FlutterSecureStorageWindowsPlugin"));
+  FlutterWebRTCPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FlutterWebRTCPlugin"));
   GalPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("GalPluginCApi"));
   LocalAuthPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("LocalAuthPlugin"));
   PermissionHandlerWindowsPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("PermissionHandlerWindowsPlugin"));
+  RecordWindowsPluginCApiRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("RecordWindowsPluginCApi"));
   SharePlusWindowsPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("SharePlusWindowsPluginCApi"));
   Sqlite3FlutterLibsPluginRegisterWithRegistrar(

windows/flutter/generated_plugins.cmake

@@ -10,9 +10,11 @@ list(APPEND FLUTTER_PLUGIN_LIST
   file_selector_windows
   flutter_inappwebview_windows
   flutter_secure_storage_windows
+  flutter_webrtc
   gal
   local_auth_windows
   permission_handler_windows
+  record_windows
   share_plus
   sqlite3_flutter_libs
   url_launcher_windows