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/archetypes.py

@@ -148,7 +148,7 @@ ARCHETYPES: dict[str, Archetype] = {
         slug="deaddeck",
         display_name="Deaddeck (Entry Point)",
         description="Internet-facing entry point with real interactive SSH — no honeypot emulation",
-        services=["real_ssh"],
+        services=["ssh"],
         preferred_distros=["debian", "ubuntu22"],
         nmap_os="linux",
     ),