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

linux/flutter/generated_plugin_registrant.cc

@@ -9,7 +9,9 @@
 #include <audioplayers_linux/audioplayers_linux_plugin.h>
 #include <file_selector_linux/file_selector_plugin.h>
 #include <flutter_secure_storage_linux/flutter_secure_storage_linux_plugin.h>
+#include <flutter_webrtc/flutter_web_r_t_c_plugin.h>
 #include <gtk/gtk_plugin.h>
+#include <record_linux/record_linux_plugin.h>
 #include <sqlite3_flutter_libs/sqlite3_flutter_libs_plugin.h>
 #include <url_launcher_linux/url_launcher_plugin.h>
 
@@ -23,9 +25,15 @@ void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) flutter_secure_storage_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "FlutterSecureStorageLinuxPlugin");
   flutter_secure_storage_linux_plugin_register_with_registrar(flutter_secure_storage_linux_registrar);
+  g_autoptr(FlPluginRegistrar) flutter_webrtc_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "FlutterWebRTCPlugin");
+  flutter_web_r_t_c_plugin_register_with_registrar(flutter_webrtc_registrar);
   g_autoptr(FlPluginRegistrar) gtk_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "GtkPlugin");
   gtk_plugin_register_with_registrar(gtk_registrar);
+  g_autoptr(FlPluginRegistrar) record_linux_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "RecordLinuxPlugin");
+  record_linux_plugin_register_with_registrar(record_linux_registrar);
   g_autoptr(FlPluginRegistrar) sqlite3_flutter_libs_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "Sqlite3FlutterLibsPlugin");
   sqlite3_flutter_libs_plugin_register_with_registrar(sqlite3_flutter_libs_registrar);

linux/flutter/generated_plugins.cmake

@@ -6,7 +6,9 @@ list(APPEND FLUTTER_PLUGIN_LIST
   audioplayers_linux
   file_selector_linux
   flutter_secure_storage_linux
+  flutter_webrtc
   gtk
+  record_linux
   sqlite3_flutter_libs
   url_launcher_linux
 )