macOS strong jail

It has been a real PITA to make `pf` in macOS reliably filter/proxy traffic for just one process due to limitations in where group selectors can be used. See also macOS's official statement "[Packet Filter is not API](https://developer.apple.com/documentation/technotes/tn3165-packet-filter-is-not-api#Overview)". There's a modern macOS swift API called [`NETransparentProxyProvider`](https://developer.apple.com/documentation/networkextension/netransparentproxyprovider).

The complexity of that approach includes:
* Getting the appropriate entitlements from Apple
* Including some Swift in the build toolchain

And, I'm unsure whether the UX would be truly seamless.

首先审查当前 macOS `pf` 过滤方案以及 issue 中描述的限制，然后阅读 Apple 的 `NETransparentProxyProvider` 文档。调查 entitlement 要求、对 Swift build-toolchain 的影响，以及由此产生的进程级代理是否能够提供无缝的 UX；完成的标准是确定实现方向，而不是留下一个未解决的可行性问题。

由索引模型根据 Issue 内容生成。