Full lab documentation and infrastructure as code

- Trino catalogs, Grafana, Spark jobs, LDAP LDIF, NPM compose
- Airflow DAG scripts, Proxmox VM inventory, network docs
- Ansible playbook, Gitea CI validate workflow
- Backup and health-check scripts, cron documentation
- Homepage DOCS tab with links to all documentation
- Extended collect-fleet-config.sh and populate-repo.py

scripts/cron/README.md

@@ -0,0 +1,14 @@
+# Cron jobs (install on atc-docker01)
+
+```cron
+# Collect fleet configs weekly (Sunday 02:00)
+0 2 * * 0  root  cd /root/lakehouse && ./scripts/collect/collect-fleet-config.sh && git add -A && git diff --staged --quiet || git commit -m "chore: weekly fleet config sync" && git push origin master
+
+# Health check every 15 minutes
+*/15 * * * * root /root/lakehouse/scripts/health/check-services.sh >> /var/log/atc-health.log 2>&1
+
+# Backup daily at 03:00
+0 3 * * * root /root/lakehouse/scripts/backup/backup-lab.sh >> /var/log/atc-backup.log 2>&1
+```
+
+Install: `crontab -e` as root on atc-docker01.