docs(webrtc_controller_flutter): 更新项目文档以反映重构后的架构

AGENTS.md 与 README.md 同步更新：根据实际代码结构重写目录树、技术栈、架构分层及编码规范，移除旧版内联示例并补充新的开发约定与代码生成命令。

webrtc_controller_flutter/lib/features/connection/domain/signal_message.g.dart

@@ -0,0 +1,29 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'signal_message.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+_$SignalMessageImpl _$$SignalMessageImplFromJson(Map<String, dynamic> json) =>
+    _$SignalMessageImpl(
+      type: json['type'] as String?,
+      fromDeviceId: json['fromDeviceId'] as String?,
+      toDeviceId: json['toDeviceId'] as String?,
+      deviceType: json['deviceType'] as String?,
+      payload: json['payload'] as String?,
+      authType: json['authType'] as String?,
+      authValue: json['authValue'] as String?,
+    );
+
+Map<String, dynamic> _$$SignalMessageImplToJson(_$SignalMessageImpl instance) =>
+    <String, dynamic>{
+      'type': instance.type,
+      'fromDeviceId': instance.fromDeviceId,
+      'toDeviceId': instance.toDeviceId,
+      'deviceType': instance.deviceType,
+      'payload': instance.payload,
+      'authType': instance.authType,
+      'authValue': instance.authValue,
+    };