Add opt-in uv-build Python prebuilt installs

[Copilot]

• Read new Windows uv-build opt-in flag comment
• Inspect current uv-build enable logic and CI
• Inspect latest CI status/logs as context
• Add Windows-specific uv-build opt-in guard
• Update CI to use the new Windows flag
• Run targeted validation
• Run automated review/security validation
• Reply to new PR comment with commit

[Copilot]

@copilot 还是不行呢
Verifying checksum 00fe7e7f4111fbde7c9b35e670f68d70b07e24572a5590b4a847828a49d2cd94...
Unpacking C:\Users\runneradmin.vfox\cache\python\cpython-3.10.20+20260414-x86_64-pc-w...

已修复 Windows uv-build pip 安装命令：不再让 cmd 直接执行带引号的 python.exe 路径，改为通过 PowerShell 以安全转义后的参数调用 Python，再运行 ensurepip/pip reinstall。对应提交：8ece92b。

[bytemain]

@copilot Verifying checksum 00fe7e7f4111fbde7c9b35e670f68d70b07e24572a5590b4a847828a49d2cd94...
Unpacking C:\Users\runneradmin.vfox\cache\python\cpython-3.10.20+20260414-x86_64-pc-windows-msvc-install_only_stripped.tar.gz...
Installing pip for uv-build Python on Windows...
& 'C:\Users\runneradmin.vfox\cache\python\v-3.10.20\python-3.10.20\python.exe' '-E' '-s' '-m' 'ensurepip' '-U' '--default-pip'
& 'C:\Users\runneradmin.vfox\cache\python\v-3.10.20\python-3.10.20\python.exe' '-E' '-s' '-m' 'pip' 'install' '--force-reinstall' '--no-index' '--find-links' 'C:\Users\runneradmin.vfox\cache\python\v-3.10.20\python-3.10.20\Lib\ensurepip_bundled' 'pip'
plugin [PostInstall] method error: C:\Users\runneradmin.vfox\plugin\python\lib\util.lua:613: Failed to install pip: pip.exe was not created after installation attempts
stack traceback:
[G]: in function 'error'
C:\Users\runneradmin.vfox\plugin\python\lib\util.lua:613: in function 'ensureWindowsUvBuildPip'
C:\Users\runneradmin.vfox\plugin\python\lib\util.lua:712: in main chunk
(tailcall): ?
[G]: ?

你参考下别的安装器呗，尤其是 uv 的，他们自己的安装是怎么安装 Pip 呢

[Copilot]

@copilot Verifying checksum 00fe7e7f4111fbde7c9b35e670f68d70b07e24572a5590b4a847828a49d2cd94...
Unpacking C:\Users\runneradmin.vfox\cache\python\cpython-3.10.20+20260414-x86_64-pc-windows-msvc-insta...

已按 uv 的方式改成先验证 python -m pip 可用，不再强依赖 pip.exe；当 uv-build/ensurepip 没生成 pip.exe 时，会在 Scripts 下创建 pip.cmd/pip3.cmd 转发到 python -m pip，这样 vfox 激活后 pip --version 也可用。对应提交：fcd4398。

[bytemain]

@copilot 再加一个标记，默认 windows 也不使用 uv-build，只有开一个标才使用，因为以前 windows 好像比较简单