Add OpenClaw AI Agent module

- Systemd service running OpenClaw gateway
- Configurable via sops secrets
- Runs on localhost:18789

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

configuration.nix

@@ -86,4 +86,22 @@
       };
     };
   };
+
+  # === OpenClaw ===
+  myModules.openclaw = {
+    enable = true;
+    port = 18789;
+    environmentFile = config.sops.templates."openclaw.env".path;
+  };
+
+  # OpenClaw secrets
+  sops.secrets.openclaw_discord_token = { };
+  sops.secrets.openclaw_openai_api_key = { };
+
+  sops.templates."openclaw.env" = {
+    content = ''
+      DISCORD_TOKEN=${config.sops.placeholder.openclaw_discord_token}
+      OPENAI_API_KEY=${config.sops.placeholder.openclaw_openai_api_key}
+    '';
+  };
 }