Add type stub generation to Harfbuzz

[vibbix]

Background

While working around with fonttools and such, the lack of proper type annotations for harfbuzz started driving me a bit crazy. I tried running it manually in my repos, but I noticed it had type issues upstream, so I wrote this PR.

Changes

• Emulated Nvidia-Cuda's stubgen-pyx usage, in setup.py
• dropped Set[int] to just Set - checked by mypy
  • I attempted to get it to extend MutableSet[Int] but that was quite troublesome
• fixed an errant ;
• Set now returns SetIter properly
• Removed an errant forward declaration of hb_color_line_t in src/uharfbuzz/charfbuzz.pxd
• added uv.lock to ignores, alongside pyi and .typed
• misc. small tweaks to improve mypy detection

Issues

1. major Currently, stubgen-pyx is a hit behind, so the use of cython 3.3.0 isn't quite here yet.

LLM Disclosure

All work was done by me, but I had Gemini/AGY double check things for me.

[vibbix]

If it's preferred, I can switch this to a github stack that splits the fixes to pyx types from the binding generator addition, so they can be reviewed separately.