config-git

1. Verify git config user.name and user.email; prompt if missing
2. git-agent init --scope --force
3. Read scopes from .git-agent/config.yml, validate naming:
   • Single words: use as-is
   • Multi-word: abbreviate to first letters (e.g., multi-word -> mw)
4. Create .claude/git.local.md from ${CLAUDE_PLUGIN_ROOT}/examples/git.local.md with validated scopes

CLI reference: ${CLAUDE_PLUGIN_ROOT}/references/cli.md