scaffold: hub-and-spoke layout, 4-network topology, 13 stack stubs

Initial structure for R&D infrastructure:

- stacks/ — 13 reusable, runnable stack stubs (kebab-case)
  cloud-and-edge: node-red, influxdb, grafana, keycloak, portainer,
                  nginx-proxy, mqtt, postfix
  cloud-only:     wireguard-server, gitea, jenkins, sql (postgres stub)
  edge-only:      wireguard-client

- cloud/ — single central hub composition with 4 networks
           (edge, app, data internal, mgmt) and include: stubs
- sites/ — per-plant edge folders (template README only for now)
- docs/architecture.md — hub-and-spoke + ingress + segmentation rationale

Network model: only nginx-proxy (80/443/8883) and wireguard-server
(51820/udp) publish ports on the cloud host. Edge nginx publishes
80/443 on plant-LAN interface only. MQTT cloud-side via nginx stream
proxy; MQTT edge-side internal-only; Postfix outbound-only.

OT layer (OPCUA, PLCs) is out of scope for this repo.

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

stacks/nginx-proxy/.env.example

@@ -0,0 +1,2 @@
+# nginx-proxy — config-file-driven, no env vars in stub
+# Domain + cert settings will land here once SSL strategy is chosen

stacks/nginx-proxy/README.md

@@ -0,0 +1,12 @@
+# nginx-proxy
+
+The single web ingress. Reverse-proxies HTTPS UIs and stream-proxies MQTT-TLS.
+
+- **Networks**: `edge` (the only port-publisher) + `app` (talks to upstream services)
+- **Host ports**: `tcp/80`, `tcp/443`, `tcp/8883`
+- **Config**:
+  - `config/nginx.conf` — base
+  - `config/conf.d/*.conf` — HTTP vhosts (one per upstream UI)
+  - `config/stream.d/mqtt.conf` — MQTT-TLS stream block, SNI route to mqtt broker
+  - `config/certs/` — TLS certs (volume-mounted from cert manager)
+- **TODO**: pick SSL strategy (acme-companion sidecar vs certbot vs internal PKI), write vhost templates per upstream

stacks/nginx-proxy/compose.yml

@@ -0,0 +1,26 @@
+# nginx-proxy — TLS reverse proxy (HTTPS + MQTT-TLS)
+# Networks: edge (port publisher) + app (proxy targets)
+# Publishes: 80, 443, 8883 on the host
+
+services:
+  nginx-proxy:
+    image: nginx:1.27-alpine
+    restart: unless-stopped
+    networks: [edge, app]
+    ports:
+      - "80:80"
+      - "443:443"
+      - "8883:8883"    # MQTT-TLS via stream{} block
+    volumes:
+      - ./config/conf.d:/etc/nginx/conf.d:ro
+      - ./config/stream.d:/etc/nginx/stream.d:ro
+      - ./config/nginx.conf:/etc/nginx/nginx.conf:ro
+      - nginx-certs:/etc/nginx/certs:ro
+    # TODO: SSL strategy (acme-companion sidecar vs certbot vs internal PKI)
+
+networks:
+  edge:
+  app:
+
+volumes:
+  nginx-certs: