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

decnet/services/ssh.py

@@ -2,7 +2,7 @@ from pathlib import Path
 
 from decnet.services.base import BaseService
 
-TEMPLATES_DIR = Path(__file__).parent.parent.parent / "templates" / "real_ssh"
+TEMPLATES_DIR = Path(__file__).parent.parent.parent / "templates" / "ssh"
 
 
 class SSHService(BaseService):