feat(cloud): harden nginx-proxy + sql foundation; HTTP-01 interim cert plan

Wire up the three foundation stacks (nginx-proxy, sql, portainer) in
cloud/compose.yml and add real configs for the first two.

nginx-proxy
- Base nginx.conf with http + stream contexts, modern TLS profile,
  client_max_body_size baseline for gitea LFS / mlflow artifacts.
- Vhosts under conf.d/: grafana, gitea, keycloak, nodered, mlflow,
  jupyter, portainer (HTTPS upstream), rabbitmq, jenkins. WebSocket
  upgrade headers where needed (grafana live, node-red editor,
  jupyterhub kernels, jenkins agents).
- conf.d/00-default.conf serves /.well-known/acme-challenge/ on :80
  and 301-redirects everything else.
- stream.d/mqtt.conf terminates MQTT-TLS at 8883, proxies to
  rabbitmq:1883 internally.
- All vhosts reference /etc/letsencrypt/live/infra/* — a stable path
  via certbot --cert-name infra, so the wildcard migration changes
  nothing in the vhost files.
- README documents: HTTP-01 SAN interim during Versio period →
  DNS-01 wildcard via certbot-dns-transip after migration; bootstrap
  procedure (self-signed fallback → real cert issuance → reload).

sql
- config/init.d/01-databases.sh provisions gitea/keycloak/mlflow
  databases + roles on first start. Idempotent only via fresh
  data volume — change the script after first run requires
  manual psql or a volume wipe.
- compose env extended with GITEA_DB_PASSWORD, KEYCLOAK_DB_PASSWORD,
  MLFLOW_DB_PASSWORD.

cloud
- include: now wires nginx-proxy + sql + portainer. Other stacks
  stay commented for future rounds.
- .env.example adds KEYCLOAK_DB_PASSWORD and sensible defaults
  (LETSENCRYPT_EMAIL, GRAFANA_ROOT_URL, KEYCLOAK_HOSTNAME,
  GITEA_ROOT_URL, POSTFIX_FROM_DOMAIN all pointing at wbd-rd.nl).
- Operator note inline: bring portainer's standalone instance down
  before deploying via cloud compose; comment its ports: block.

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

stacks/nginx-proxy/config/conf.d/00-default.conf

@@ -0,0 +1,15 @@
+# Port 80 — ACME HTTP-01 challenges + force HTTPS redirect for everything else.
+
+server {
+    listen 80 default_server;
+    server_name _;
+
+    location /.well-known/acme-challenge/ {
+        root /var/www/certbot;
+        default_type "text/plain";
+    }
+
+    location / {
+        return 301 https://$host$request_uri;
+    }
+}