chore(rig): run both central nodes with DisableLogin=true so the local Central UI needs no login

Rig-only posture, set in the tracked docker/central-node-{a,b}/appsettings.Central.json
so it survives deploy.sh / container recreates (it used to be a throwaway compose
override on central-a alone). Both nodes so Traefik on :9000 is login-free
regardless of which node is active. POST /auth/login still answers 302, so the
Playwright fixture login is unaffected; LoginTests will fail on this rig by design.
Documented in the scadabridge-cluster-ops skill.

Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29

docker/central-node-a/appsettings.Central.json

@@ -44,7 +44,8 @@
         "_comment_ServiceAccountPassword": "Supplied as ScadaBridge__Security__Ldap__ServiceAccountPassword env override in docker-compose.yml (dev-only-insecure)."
       },
       "Auth": {
-        "DisableLogin": false,
+        "_comment": "RIG-ONLY: both central nodes run login-disabled so the local Central UI (http://localhost:9000 via Traefik, or 9001/9002 direct) needs no LDAP login. Dev/test only — the real login path is exercised by docker-env2 and the unit tests.",
+        "DisableLogin": true,
         "User": "multi-role"
       },
       "_comment_JwtSigningKey": "Supplied as ScadaBridge__Security__JwtSigningKey env override in docker-compose.yml (dev-only-insecure).",

docker/central-node-b/appsettings.Central.json

@@ -44,7 +44,8 @@
         "_comment_ServiceAccountPassword": "Supplied as ScadaBridge__Security__Ldap__ServiceAccountPassword env override in docker-compose.yml (dev-only-insecure)."
       },
       "Auth": {
-        "DisableLogin": false,
+        "_comment": "RIG-ONLY: both central nodes run login-disabled so the local Central UI (http://localhost:9000 via Traefik, or 9001/9002 direct) needs no LDAP login. Dev/test only — the real login path is exercised by docker-env2 and the unit tests.",
+        "DisableLogin": true,
         "User": "multi-role"
       },
       "_comment_JwtSigningKey": "Supplied as ScadaBridge__Security__JwtSigningKey env override in docker-compose.yml (dev-only-insecure).",