Clean up Helm directory and update documentation

- Removed deprecated chart files from helm/ root directory
- Updated all Helm documentation to reference warehouse13 chart
- Changed database name from 'datalake' to 'warehouse13' in values.yaml
- Updated helm command examples in SUMMARY.md
- Fixed migration instructions in helm/README.md
- Updated PostgreSQL backup/restore commands with correct database name

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

helm/warehouse13/README.md

@@ -328,10 +328,10 @@ kubectl delete pvc -l app.kubernetes.io/instance=my-warehouse13
 
 ```bash
 # Create backup
-kubectl exec -it warehouse13-postgres-0 -- pg_dump -U user datalake > backup.sql
+kubectl exec -it warehouse13-postgres-0 -- pg_dump -U user warehouse13 > backup.sql
 
 # Restore
-kubectl exec -i warehouse13-postgres-0 -- psql -U user datalake < backup.sql
+kubectl exec -i warehouse13-postgres-0 -- psql -U user warehouse13 < backup.sql
 ```
 
 ### MinIO Backup