closes #3: add windows version for transport/tcp.go

[5amu]

The _windows.go file is compiled only when GOOS=windows and does not depend on CGO. It relies exclusively on Go’s standard library and supports proxy configuration via environment variables.

I performed basic testing, although I do not yet have a dedicated lab environment. The implementation follows the same approach I used in a previous pet project (https://github.com/5amu/goad). I'm revisiting it to use this library and start developing it again, so thank you for that!

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[psycep]

Hey @5amu thanks for opening this, the _windows.go split using x/net/proxy.Dial was the right call. I ended up going a bit wider with #10, which covers the same Windows unblock plus an explicit -proxy flag, UDP handling, and chaining with proxychains. The build tag there is !cgo || windows so CGO_ENABLED=0 Linux also builds, which yours couldn't hit because _unix.go still required cgo. Keeping this one open for now, once #10 lands I'll close it and link the merge commit. If you want to take a look at #10 or have feedback on the approach, please do. Thanks again!

[psycep]

Closing as landed in #10 (merge commit 8f997a5).