Create groups

Create up to BATCH_MAX_ITEMS groups in a single request.

Each item is processed independently — a failure on one row does not abort the rest. Response is 200 if all items succeed, 207 if any fail, 400 if the request envelope is empty or over the cap.

Within-batch duplicate detection is first-wins on name: the first occurrence of a name is processed; subsequent occurrences are pre-marked as duplicate_in_batch without reaching the service.

See api_v2/docs/batch-responses.md for the 200/207/400 status convention and per-item error code vocabulary.

Required OAuth scope: student-groups:write