feat(client): P6 设置项落地真实行为(#6 6F,本地部分)

- settings_provider:三开关 shared_preferences 持久化 + 副作用落地:
  killSwitch→VpnBridge.setKillSwitch(on:);autostart→桌面原生登录项
  (launch_at_startup);smartRoute 持久化为偏好(连接时作 split_cn,见 #5)。
- settings_page → ConsumerWidget,开关接 settingsProvider;协议标签
  WireGuard→REALITY/Hysteria2;版本号取 pubspec(package_info_plus)。
- 新依赖:shared_preferences / package_info_plus / launch_at_startup。

flutter analyze 0 error;114 tests passed;settings golden 重生成。
待办:#5 智能分流的 server 端 geoip-cn 下发 + autostart 真机验证(需 release .app)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -6,7 +6,11 @@ import FlutterMacOS
 import Foundation
 
 import flutter_secure_storage_macos
+import package_info_plus
+import shared_preferences_foundation
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   FlutterSecureStoragePlugin.register(with: registry.registrar(forPlugin: "FlutterSecureStoragePlugin"))
+  FPPPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FPPPackageInfoPlusPlugin"))
+  SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
 }