Get Matrix Cells Batch

Batch fetch matrix cells using entity_set_filters (entity-ref based).

Frontend provides entity_set_filters to specify which entities to fetch cells for. Finds all cells that reference any of the specified entities (role-agnostic).

Example: POST /matrices/1/cells/batch Body: { "entitySetFilters": [ {"entitySetId": 1, "entityIds": [10, 11, 12]}, {"entitySetId": 2, "entityIds": [20, 21, 22]} ] } Returns all cells that reference any of those entities in any role.