docs(windows): 跟踪主窗口圆角与外框问题

[Cooper-X-Oak]

摘要

Fixes #141

这个 draft PR 用来承接 Windows 主窗口圆角贴合与外框不完整问题的后续修复生命周期。
当前阶段只放 tracking artifact，不引入功能性修复；真正转为 ready 之前，需要把 issue #141 里的 root cause、platform scope、lifecycle differences 和验证证据收齐。
当前认领方式采用 PR 占位承接，因为上游仓库暂不可直接把 Cooper-X-Oak 设为 assignee。

修复 / 新增 / 改进

• 新增 docs/windows-ui-tracking/issue-141-main-frame.md 作为 tracking note
• 记录 macOS design intent 与 Windows 偏差、Windows-only symptom 与 cross-platform risk
• 记录 merge rule：只有该 PR 最终 merge，issue [windows] 主窗口圆角贴合与外框不完整 #141 才算生命周期闭环

兼容

• 不包含：Windows UI 代码修复本身
• 对现有用户 / 本地环境 / 构建流程的影响：仅新增 tracking 文档，占位用；no runtime impact

测试计划

• 命令：检查 PR 模板字段、issue 绑定、draft 状态是否完整
• 结果：当前 draft PR 仅包含 tracking 文档，适合在修复开始前持续收敛 scope 与目标
• 证据路径：docs/windows-ui-tracking/issue-141-main-frame.md

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[Cooper-X-Oak]

Closing this draft PR as a duplicate placeholder.\n\nThe earlier canonical pair is issue #127 + draft PR #125. The newer analysis from #141/#144 has been folded back into that earlier track.

[Cooper-X-Oak]

Closing as duplicate of draft PR #125, which already tracks the earlier canonical issue #127.