## Summary
The interface here is intentionally a bit more limited than `uv pip
compile`, because we don't want `requirements.txt` to be a system of
record -- it's just an export format. So, we don't write annotation
comments (i.e., which dependency is requested from which), we don't
allow writing extras, etc. It's just a flat list of requirements, with
their markers and hashes.
Closes#6007.
Closes#6668.
Closes#6670.
