docs: Windows / WSL FAQ bullets for uv + mutiny

[CodewithJha]

Problem

GOOD_FIRST_ISSUES #6: README FAQ lacks Windows/WSL notes for uv / venv. Cold-start friction for a large contributor OS share.

Repository evidence

• README.md FAQ / Install sections
• docs/COLD_START.md
• Catalog cli: strengthen mutiny init next-step hint + test coverage #6

Proposed direction

Add ~3 bullets: install uv on Windows, WSL recommendation, path/python notes for mutiny entrypoint. Do not invent unsupported claims.

Acceptance criteria

• FAQ bullets present and accurate
• Link to astral uv Windows docs if helpful
• No false PyPI/product claims

Difficulty

XS · docs · good first issue