fix: mount correct SSH key (rwadurian_ed25519) in agent-service

The IT0 server has its own id_ed25519 which differs from the local
key that's authorized on RWADurian servers. Use a dedicated key file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

deploy/docker/docker-compose.yml

@@ -122,7 +122,7 @@ services:
       - ${HOME}/.claude:/home/appuser/.claude
       - ${HOME}/.claude.json:/home/appuser/.claude.json
       - claude_tenants:/data/claude-tenants
-      - ${HOME}/.ssh/id_ed25519:/tmp/host-ssh-key:ro
+      - ${HOME}/.ssh/rwadurian_ed25519:/tmp/host-ssh-key:ro
     environment:
       - DB_HOST=postgres
       - DB_PORT=5432