Add n8n service to docker-compose

- docker-compose: n8n container (port 5678) with PostgreSQL backend
- n8n/: 7 TypeScript workflow files + import script + README
- Workflows: 4 CMS BI data ingestion + 3 email reports
- README: updated with n8n env vars and port
- .dockerignore: exclude import.sh from container

.dockerignore

@@ -7,3 +7,4 @@ __pycache__/
 *.log
 .dbpass
 migrations/_migrations*
+n8n/import.sh