v0.6.0

Peen now ships a dedicated agent package for configuring and operating Peen.

- Replaces the inherited Servicepack agent metadata with the `peen` skill for
  Claude, Codex, and OpenClaw. The skill covers provider configuration, Docker
  deployment, WebSocket turns, durable session control, and workspace harness
  layers.
- Adds marketplace installation guidance to the README. The central marketplace
  entry follows this release.
- Includes the embedded base `AGENTS.md` in clean checkouts. Lint now rejects a
  Go embedded asset that Git ignores, preventing a local build from masking a
  CI compile failure.