Add a column

Rides the versioned delta column-ops engine; response includes createdColumnId. Computed columns MUST carry a config, because the values cannot be inferred and an unconfigured computed column would stay blank forever; a missing key answers 400. rollup needs source_scope ("activities" or "activity_details") and target_field_id (a column id from the activity group), optionally source_group_id to scope it to one group and aggregation (sum, avg, median, min, max, count, concatenate, unique; defaults to sum). lookup needs source_linked_column_id (a linked_record column on this same module) and display_field_map keyed by TARGET MODULE ID to the column id being read, plus an optional aggregation. formula needs expression, referencing other columns as {column-id}. linked_record takes target: { moduleId, level: "record" } (or level "activity" with activityGroupId); a column links to ONE module, so target_module_ids with several modules answers 400 linked_record_multiple_targets (one id is still accepted and stored as target; reads return target_module_ids for a record target, read-only). Get the ids from GET /modules/{moduleId}/columns and GET /modules/{moduleId}/activity-groups.

Requires the schema:write token scope.

Admin-role principals only.