Eliminate CLI top-level await startup warning and stop preselecting GUI Apps on Linux

[Copilot]

• Inspect the review feedback on repeated zsh checks in the CLI
• Simplify CLI zsh gating to a single pre-switch check with a generic message
• Update focused CLI tests for the simplified behavior
• Run targeted Vitest coverage for CLI and setup flows
• Run final review and reply to the addressed PR comment

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[ChangeHow]

你这里有必要一行行都写一遍吗？最前面写一遍不就行了，不在乎标题，不是 zsh 就退出提示一个通用信息就行了 @copilot

[Copilot]

已按这个方向收敛，src/cli.js 现在改成在进入 switch 前统一做一次通用的 zsh 检查，help 不受影响，不再每个 command 单独写一遍。对应提交：49be73e。

截图：https://github.com/user-attachments/assets/8eb3f88c-8fd9-44b5-ad71-7c8c97c269bd

[ChangeHow]

@copilot 我更新了代码，这下直接退出了：
chenzihao.house@n37-017-250 ~ % curl -fsSL https://raw.githubusercontent.com/ChangeHow/suitup/main/install.sh | bash
Downloading ChangeHow/suitup@main...
Extracting archive...
Installing suitup dependencies...

added 54 packages in 683ms
Launching suitup inside zsh...
┌ Suit up!
│
◆ Select setup steps:
│ ◼ Bootstrap (Package manager + Zsh)
│ ◼ Zsh Config Structure (~/.config/zsh/)
│ ◼ Plugin Manager (recommended zinit or skip)
│ ◼ CLI Tools (bat, eza, fzf, fd, zoxide, atuin...)
│ ◻ GUI Apps
│ ◼ Frontend Tools (fnm, pnpm, git-cz)
│ ◼ Shell Aliases (git, eza, fzf shortcuts)
│ ◻ SSH Key
│ ◻ Vim Config
│ ◻ Dock Cleanup
└
chenzihao.house@n37-017-250 ~ %
重新创建一个 PR 帮我解决这个问题