feat: Add Metabase as a new service

Adds the Metabase service to the Docker Compose setup.

- Creates a compose.yaml and .env.example for Metabase.

- Adds Metabase to the list of deployed services in the Ansible configuration.

- Updates .gitignore

inventories/hetzner/host_vars/cit-docker-host.yaml

@@ -7,3 +7,5 @@ docker_compose__projects:
     files_directory: ../docker_compose_applications/n8n
   - name: oauth2-proxy
     files_directory: ../docker_compose_applications/oauth2-proxy
+  - name: metabase
+    files_directory: ../docker_compose_applications/metabase