malvin should engage an agent to help with `init`. An agent would
- Determine what should go in .malvin/checks when we call init on an existing repo.
Does the repo use different linters than malvin's defaults? How are unit tests
called? This information might be in the pre-commit hooks -- if they're used at all.
- malvin should run a kpop loop with a prompt, `default_prompts/init_constraints.md` (analogous to
`code_constraints.md` and `tidy_constraints.md`), designed for this purpose.
- The prompt should suggest our current default as fallbacks.
- Empty repos should get our defaults (ruff, kiss, etc.)