优化配置，修复 demo bug

1，network 框架完善
2，websocket 机制完善
3，设计文档整理到架构文档
4，脚本，配置完善

packages/notification_sdk/ios/Classes/NotificationSdkPlugin.swift

@@ -1,4 +1,4 @@
-import Flutter
+@preconcurrency import Flutter
 import UIKit
 
 public class NotificationSdkPlugin: NSObject, FlutterPlugin {

packages/notification_sdk/ios/notification_sdk.podspec

@@ -19,7 +19,7 @@ A new Flutter plugin project.
 
   # Flutter.framework does not contain a i386 slice.
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
-  s.swift_version = '5.0'
+  s.swift_version = '6.2'
 
   # If your plugin requires a privacy manifest, for example if it uses any
   # required reason APIs, update the PrivacyInfo.xcprivacy file to describe your