feat(desktop): copy diagnostics on demand

[M4n5ter]

Fixes #3425

English

Summary

• Upgrade the existing environment-summary actions in About and the command palette to copy a complete diagnostic report on demand.
• Reuse the bounded, redacted Desktop and Runtime Host diagnostic pipeline already used by error surfaces.
• Keep Desktop diagnostics available while About metadata is loading or unavailable and when the active Runtime Host is unavailable; reports remain clipboard-only and are never uploaded automatically.

Verification

• npm run lint
• npm run format:check
• npm --workspace @maka/desktop run typecheck
• npm --workspace @maka/desktop run test:dist — 1027 passed
• node --test apps/desktop/dist/main/tests/about-settings-page.test.js apps/desktop/dist/main/tests/main-process-diagnostics.test.js — 10 passed

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex assisted with implementation, tests, review, and pull request drafting; the human contributor remains responsible for the change.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

中文

概要

• 将“关于”页和命令面板中原有的环境信息复制入口升级为可随时主动复制完整诊断报告。
• 复用错误界面已经使用的有界、脱敏 Desktop 与 Runtime Host 诊断链路。
• 在“关于”元数据加载中或不可用，以及当前 Runtime Host 不可用时，仍可复制 Desktop 侧诊断；报告只写入剪贴板，不会自动上传。

验证

• npm run lint
• npm run format:check
• npm --workspace @maka/desktop run typecheck
• npm --workspace @maka/desktop run test:dist — 1027 项通过
• node --test apps/desktop/dist/main/tests/about-settings-page.test.js apps/desktop/dist/main/tests/main-process-diagnostics.test.js — 10 项通过

AI 使用

Codex 辅助了实现、测试、审查和 PR 文案；贡献者本人仍对该变更负责。AI 使用选项已在英文部分勾选。

检查清单

• 测试覆盖该变更，并会在缺少实现时失败。
• lint、format、typecheck 与受影响测试均已在本地通过。
• 本 PR 包含用户可见的行为变更，已在概要中说明。