update-gitignorelisted
Install: claude install-skill FradSer/dotclaude
1. Preserve custom rules from existing .gitignore
2. `git-agent init --gitignore --force`
3. On auth error (401), retry with `--free`
4. Re-add preserved custom rules
5. Show diff
CLI reference: `${CLAUDE_PLUGIN_ROOT}/references/cli.md`