Cleanup Orphaned Entities

Clean up all orphaned entities from the graph.

This safely removes Entity nodes that have no relationships:

• No MENTIONS from any Memory
• No RELATES_TO connections to other entities
• No HAS_LABEL relationships

This operation only affects Entity nodes and will not delete:

• Internal system nodes (GraphMeta, migrations, etc.)
• Label nodes
• Community nodes
• Memory nodes

curl -X DELETE "http://127.0.0.1:14242/graph/orphans"

{
  "success": true,
  "deleted_count": 0,
  "message": "string"
}