Tighten the installation/adoption path for people who want to use Proof Loop inside another repository.
Acceptance criteria:
- README clearly distinguishes clone-and-run, copy-folder, and skill-install usage.
- The quickest path stays stdlib-only and does not require packaging ceremony.
- Docs include one command sequence that creates a task and one that checks it.
Tighten the installation/adoption path for people who want to use Proof Loop inside another repository.
Acceptance criteria: