curl --request POST \
  --url https://api.example.com/api/playground/sessions/{session_id}/splits \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "target_column": "<string>",
  "target_label_column": "target_label",
  "split_column": "split",
  "include_train": true,
  "include_val": true,
  "include_test": true,
  "train_ratio": 0.7,
  "val_ratio": 0.15,
  "test_ratio": 0.15,
  "random_state": 42
}
'

{
  "session_id": "<string>",
  "row_count": 123,
  "target_column": "<string>",
  "target_label_column": "<string>",
  "split_column": "<string>",
  "splits": [
    "<string>"
  ],
  "split_counts": {},
  "split_ratios": {},
  "overall_target_distribution": {},
  "target_distribution_by_split": {},
  "split_balance": {},
  "balance_quality": "<string>",
  "balance_score": 123,
  "balance_feedback": "<string>",
  "stratified": true,
  "worst_split": "<string>",
  "worst_split_tvd": 123,
  "worst_split_gap": 123,
  "warning": "<string>"
}