feat(cloud): single-shot deploy.sh + FROST stack + healthchecks

Stage 5 — make the cloud composition spin up in one command and add
the SensorThings (FROST) stack as a fully segregated tenant.

cloud/deploy.sh — idempotent, 7-step bring-up:
  preflight → validate → up + wait → cert state → issue/renew →
  service status → endpoint smoke test. Reissues LE cert only when
  current issuer no longer matches ACME_CA_URI. Move-aside-then-
  restore-on-failure so the bootstrap cert survives a failed certbot.

stacks/frost — new stack, segregated from shared sql/rabbitmq:
  - dedicated postgis container (frost-db)
  - dedicated internal mosquitto bus (frost-mosquitto)
  - frost-http + frost-mqtt on a private frost-internal network,
    joined to cloud-app only for nginx ingress at frost.wbd-rd.nl
  - shared mosquitto stack deleted; rabbitmq remains the only public
    MQTT broker (mqtt.wbd-rd.nl:8883 via stream proxy)

stacks/sql — pg_isready healthcheck so keycloak/gitea/mlflow can gate
on service_healthy via cloud-level depends_on overrides.

stacks/nginx-proxy:
  - nginx-init service generates a self-signed bootstrap cert on
    fresh deploy so nginx starts before certbot has issued a real one
  - frost.wbd-rd.nl vhost (/FROST-Server → frost-http:8080,
    /mqtt → frost-mqtt:9876 WebSocket)

stacks/mlflow — custom Dockerfile (upstream + psycopg2-binary) so the
official image can speak to the shared sql backend.

stacks/jupyterhub — DummyAuthenticator stub gated by
JUPYTERHUB_ADMIN_PASSWORD; TODO comments point at OIDC + DockerSpawner.

stacks/rabbitmq — config/{enabled_plugins,rabbitmq.conf} stubs
(management + mqtt plugins, MQTT auth required).

stacks/portainer — ports unpublished; nginx now the only ingress.

stacks/node-red — pin to 4.1 (the floating "4" tag does not exist).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cloud/.env.example

@@ -68,5 +68,12 @@ MLFLOW_DB_USER=mlflow
 MLFLOW_DB_PASSWORD=
 
 # JupyterHub
+# STUB AUTH: DummyAuthenticator. Set a strong shared password — any username + this password logs in.
+# Replace with Keycloak OIDC (GenericOAuthenticator) before exposing to users beyond the cloud operator.
 JUPYTER_NOTEBOOK_IMAGE=jupyter/datascience-notebook:latest
 JUPYTERHUB_ADMIN_USERS=
+JUPYTERHUB_ADMIN_PASSWORD=
+
+# FROST (SensorThings — dedicated postgis + internal mosquitto bus, ingressed at frost.wbd-rd.nl)
+FROST_DB_PASSWORD=
+FROST_SERVICE_ROOT_URL=https://frost.wbd-rd.nl/FROST-Server