chore: migrate desktop runtime to dsh alpha.2

[t4wefan]

Summary / 摘要

• Pin the upstream submodule to dsh-v0.1.2-alpha.2 and vendor its 245-package runtime closure.
  将上游子模块固定到 dsh-v0.1.2-alpha.2，并同步 245 个运行时包。
• Align shared framework dependencies and add the new dsh-util-time peer required by alpha.2.
  对齐共享框架依赖，并加入 alpha.2 新要求的 dsh-util-time peer。
• Rebase only the six OS/Electron patches required by Desktop: hidden Windows child processes, native directory selection and unreadable-directory filtering, plus Electron browser-helper environment isolation.
  仅迁移六个 Desktop 正常运行所需的系统/Electron 补丁：Windows 子进程隐藏、原生目录选择与不可读目录过滤、Electron 浏览器 helper 环境隔离。
• Restore the three alpha.1 settings runtime exports as deprecated additive shims for existing profile plugins. settingsNamespace keeps alpha.2 validation, installSettingsSection delegates to SettingsProvider.installSection, and deepEqualJson re-exports the alpha.2 util implementation. This fixes the reproduced startup failure in npm-latest dshmarket@1.38.0 without rewriting or downgrading a user profile.
  以 deprecated、纯加法 shim 恢复 alpha.1 的三个 settings 运行时导出；修复 npm 最新版 dshmarket@1.38.0 已复现的启动失败，不改写或降级用户 profile。
• Migrate Desktop and Community Market themselves to the native alpha.2 settings namespace API.
  将 Desktop 与 Community Market 自身迁移到 alpha.2 原生 settings namespace API。
• Drop the cosmetic upstream settings-icon patch.
  删除纯外观性质的上游设置图标补丁。

Validation / 验证

• corepack yarn install --immutable
• clean-tarball git apply --check --whitespace=error-all for the settings compatibility patch
• targeted legacy settings / dshmarket module-instantiation / package tests: 47 passed, 1 skipped
• corepack yarn check
  • Community Market: 23 files, 268 tests passed
  • Desktop: 103 files, 991 tests passed, 4 skipped
  • runtime closure: 229 first-party nodes
  • vendored runtime: 245 packages verified
• corepack yarn dist:mac-smoke before the additive settings shim
  • universal unsigned DMG built, mounted, inspected, and detached successfully

Remaining platform checks / 待实机验证

• Restart Electron and verify yarn dev against a real profile after the reproduced settings import failure
• onboarding in compatibility, extended, and advanced modes
• recovery flow with other incompatible third-party plugins
• trusted-certificate LAN HTTPS/WSS heartbeat and reconnect
• Windows installer/package behavior on Windows CI or a Windows machine

The macOS smoke intentionally skips signing and notarization. No Windows package was built on macOS.