Docs-as-code: full deploy configs, compose stacks, and DR guide

- Add root README and docs/ (architecture, hosts, disaster-recovery, operations)
- Add compose/ for superset, forgejo, lam, cadvisor; unified deploy compose
- Add scripts/deploy (deploy-atc-docker01.sh, container inventory export)
- Add inventory/containers-atc-docker01.json snapshot
- Add config READMEs for kafka and airflow; .env.example; expand .gitignore
- Sync atclab helper scripts; update homepage/superset compose with env support

.env.example

@@ -0,0 +1,15 @@
+# Kopieer naar .env op atc-docker01: cp .env.example .env
+
+# Superset (compose/superset)
+SUPERSET_SECRET_KEY=change-me-to-a-long-random-string
+
+# Homepage (optioneel)
+HOMEPAGE_ALLOWED_HOSTS=atc-docker01.dell-atc.lan,localhost
+
+# Proxmox API — ook in config/homepage/proxmox.yaml
+# PROXMOX_URL=https://10.0.10.65:8006
+# PROXMOX_TOKEN=root@pam!homepage
+# PROXMOX_SECRET=
+
+# Kafka connectors — vervang in config/kafka/*.json bij deploy
+# DATABASE_PASSWORD=