feat: sync mac installer with local shell setup

[dmoliveira]

Summary

• sync the macOS installer with the repo-managed shell, editor, terminal, and helper-script templates
• install optional macOS window workflow tools via Homebrew without auto-starting yabai or skhd
• document the new install behavior in README.md and docs/getting-started.md

Validation

• Lint: cargo clippy --version
• Lint: git diff --check
• Lint: bash -n install_my_programs_mac
• Lint: zsh -n run_commands/my_zshrc
• Test: PATH="/opt/homebrew/bin:$PATH" pre-commit run --files README.md docs/getting-started.md install_my_programs_mac run_commands/codex_config.toml run_commands/my_startship.toml run_commands/my_zshrc
• Test: TOML parse check returned TOML OK
• Test: ./install_my_programs_mac --dry-run

[dmoliveira]

Superseded by #128 after rebasing onto current master.