feat: add conflicts_with notes for pipx/uvx installs in formula caveats

[ulises-jeremias]

Context

Users may install via uvx/pip and Homebrew simultaneously. Add caveats/conflicts documentation in the formula README or caveats block.

[ulises-jeremias]

Taking this one myself — Homebrew/AUR packaging work needs org-specific permissions (tap publish, AUR credentials, distribution secrets), so it is not a good fit for external contributors right now.

If you want to help with related docs/tests that do not require those secrets, ping me in Discord and we can carve out a safe slice.