[UX] Homebrew installation instructions reference a non-existent tap

[coderabbitai]

Summary

The README installation section includes:

brew install yourusername/tap/git-copilot

yourusername is a literal placeholder that was never replaced. No Homebrew tap exists for this project.

Impact

• Copy-paste installation fails for all macOS users who choose Homebrew
• Same issue exists in the pre-built binary download URL (yourusername placeholder)

Recommended Fix

Either:

1. Create an actual Homebrew tap and update the README with the real tap URL
2. Remove the Homebrew and binary sections until they are ready, keeping only the npm install -g path

Backlink: #1