refactor(ssh): consolidate real_ssh into ssh, remove duplication

real_ssh was a separate service name pointing to the same template and
behaviour as ssh. Merged them: ssh is now the single real-OpenSSH service.

- Rename templates/real_ssh/ → templates/ssh/
- Remove decnet/services/real_ssh.py
- Deaddeck archetype updated: services=["ssh"]
- Merge test_real_ssh.py into test_ssh.py (includes deaddeck + logging tests)
- Drop decnet.services.real_ssh from test_build module list

tests/test_build.py

@@ -51,7 +51,6 @@ MODULES = [
     "decnet.services.imap",
     "decnet.services.pop3",
     "decnet.services.conpot",
-    "decnet.services.real_ssh",
     "decnet.services.registry",
 ]