Get KB Stats

curl --request GET \
  --url https://eu-vg-edge.moeaymandev.workers.dev/v2/agents/{agent_id}/stats/kb \
  --header 'Authorization: Bearer <token>'

{
  "success": true,
  "message": "Agent KB statistics retrieved successfully",
  "data": {
    "charCount": 123,
    "docsCount": 123
  }
}