Class MoveListMembersAction

Move a set of records from one list to another. Implemented as a thin wrapper over ListOperations semantics:

1. Insert the records into TargetListID (additive — silent skip on duplicates).
2. If Mode = 'move' (default), remove them from SourceListID. Removal goes through the same drop-guard contract; passing ConfirmDrops: true is required to actually delete.

For Mode = 'copy', step 2 is skipped — the records end up in both lists. The RecordIDs input is a JSON-stringified string array matching the canonical MJ: List Detail.RecordID format.