fix(windows): 收敛 clipboard restore 并发恢复竞态

[appergb]

摘要

Closes #167

把 Windows/Linux 路径里的“恢复用户原剪贴板”从无界多线程改成单条最新恢复链：连续多次听写时，只允许最新一轮 restore 真正落地，但保留最早那份原始剪贴板快照。

改动

• schedule_clipboard_restore 改为分配递增 restore_id
• 用进程级 PENDING_CLIPBOARD_RESTORE 记录“当前批次的最早原始剪贴板 + 最新 restore id”
• 旧 restore 线程睡醒后若发现自己不是最新批次，直接退出，不再写系统剪贴板
• 最新批次仍保留现有保护：只有剪贴板内容还等于最后一次插入文本时才恢复

验证

• cargo check --manifest-path src-tauri/Cargo.toml ✅
• 最终 Windows 时序由 CI / 实机验证

@codex review

[sourcery-ai]

Sorry @appergb, you have reached your weekly rate limit of 500000 diff characters.

Please try again later or upgrade to continue using Sourcery

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Swish!

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".