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

.gitignore

@@ -1,7 +1,27 @@
-# Runtime logs (not config)
+# Runtime logs
 config/homepage/logs/
 *.log
 
+# Secrets (lokaal op host, niet committen indien je .env gebruikt)
+.env
+.env.local
+.env.*.local
+
 # OS / editor
 .DS_Store
 *~
+.idea/
+.vscode/
+
+# Python
+__pycache__/
+*.pyc
+.venv/
+
+# Docker build cache
+**/.build/
+
+# Backup dumps (bewust buiten git)
+backup/
+*.tgz
+*.tar.gz