feat(cliproxy): 日志面板展示后端透传的具体错误原因

[g1331]

Summary

接 PR #200：v0.5.1 已经把 CLIProxyAPI 上游 4xx 的错误正文拼到 CliproxyManagementApiError.message 上，但前端日志面板仍只展示通用的 logsLoadFailed 文案，把真正的根因（如 logging to file disabled）吞掉。

现在 panel 在 isError 时额外展示 error.message —— 例如 CLIProxyAPI 端未启用 LoggingToFile 时，用户能直接在 UI 上看到 "logging to file disabled"，不再需要去翻后端日志才知道为什么 502。

Changes

• src/components/admin/cliproxy-instance-logs-panel.tsx：错误态新增第二行展示 error.message，灰字、可换行
• 同步组件测试覆盖：错误带 message 时被渲染、错误不带 message 时仍展示通用标题

Test plan

• pnpm exec tsc --noEmit
• pnpm lint
• pnpm test:run tests/components/cliproxy-instance-logs-panel.test.tsx（8 通过）
• CI 全绿

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.44%. Comparing base (de6385b) to head (414d62e).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #201      +/-   ##
==========================================
- Coverage   74.44%   74.44%   -0.01%     
==========================================
  Files         160      160              
  Lines       11624    11626       +2     
  Branches     3980     3982       +2     
==========================================
+ Hits         8654     8655       +1     
  Misses       1731     1731              
- Partials     1239     1240       +1     

Flag	Coverage Δ
verify	74.44% <100.00%> (-0.01%)	⬇️

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