feat: add startup update checker using HMBSbige.UpdateChecker

[Copilot]

Adds automatic update checking on startup with configurable settings, using HMBSbige.UpdateChecker to query GitHub Releases.

Contract & Service Layer

• IUpdateAppService in Application.Contracts with CheckForUpdateAsync(bool includePreRelease, CancellationToken)
• UpdateAppService implementation using GitHubReleasesUpdateChecker and IHttpClientFactory (consistent with StunServerListAppService)
• 15s HTTP timeout; tag-to-version strips v prefix

Configuration

• AppConfig extended with AutoCheckUpdate (default: true), CheckUpdateInterval (default: 1h), IncludePreRelease (default: false), LastUpdateCheckTime (DateTimeOffset? for timezone correctness)
• Settings persisted via existing IAppConfigManager reactive pipeline

ViewModel

• SettingsViewModel: new reactive properties, CheckUpdateCommand, CheckForUpdateOnStartupAsync with interval gating
• MainWindowViewModel.InitializeAsync: fires startup check via Task.Run to avoid blocking UI
• Silent mode: startup check swallows exceptions and skips "no update" notification; manual check shows both outcomes

View

• Update section at top of Settings tab: version display, check/homepage buttons, auto-check toggle, interval input, pre-release toggle
• Localization strings added for both en and zh-Hans

// Startup check — runs on background thread, respects interval
_ = Task.Run(() => SettingsViewModel.CheckForUpdateOnStartupAsync(config, cancellationToken), cancellationToken);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• 1.1.1.1
  • Triggering command: REDACTED, pid is -1 (packet block)
  • Triggering command: /home/REDACTED/work/NatTypeTester/NatTypeTester/tests/UnitTest/bin/Debug/net10.0/UnitTest /home/REDACTED/work/NatTypeTester/NatTypeTester/tests/UnitTest/bin/Debug/net10.0/UnitTest @@ /tmp/tmpPVfC4W.tmp -collect-logs (packet block)
• av-build-tel-api-v1.avaloniaui.net
  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.2/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll (dns block)
• stun.hot-chilli.net
  • Triggering command: /home/REDACTED/work/NatTypeTester/NatTypeTester/tests/UnitTest/bin/Debug/net10.0/UnitTest /home/REDACTED/work/NatTypeTester/NatTypeTester/tests/UnitTest/bin/Debug/net10.0/UnitTest @@ /tmp/tmpPVfC4W.tmp -collect-logs (dns block)
• www.nuget.org
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>feat: 新增启动时检查更新</issue_title>
<issue_description>- 设置增加检查更新按钮、用于跳转到主页的按钮、显示当前版本、现在最新版本

• 设置增加检查更新相关的3个选项：启动时自动检查更新（默认开启），启动时自动检查更新间隔（默认1小时，避免频繁启动时重复检查），检查 prerelease 更新（默认不开启）
• 使用 HMBSbige.UpdateChecker 包
• 检查更新结果用已有的 INotificationService 通知，其中如果是启动时检查更新无更新时不通知
• 定义 IUpdateService 在 Application.Contracts 层
• 实现 UpdateService 在 Application；HttpClient 的创建应与现有的 StunServerListAppService.CreateHttpClient复用

注意：

• 网络异常处理: 网络请求设置合理超时，异常不应影响应用正常使用
• 时间存储: LastUpdateCheckTime 使用 DateTimeOffset 以正确处理时区
• 线程安全: 配置读取和更新检查应在后台线程执行，避免阻塞 UI</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes feat: 新增启动时检查更新 #305

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