Introduces the 'real_ssh' service plugin backed by a genuine OpenSSH
server (not cowrie), and the 'deaddeck' archetype that uses it. The
container ships with a lived-in Linux environment and a deliberately
weak root:admin credential to invite exploitation.
- templates/real_ssh/: Dockerfile + entrypoint (configurable via env)
- decnet/services/real_ssh.py: BaseService plugin, service_cfg supports
password and hostname overrides
- decnet/archetypes.py: deaddeck archetype added
- tests/test_real_ssh.py: 17 tests covering registration, compose
fragment structure, overrides, and archetype
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>