Adds the additive v7 TableOperation request and HostApi::table_operation for
layer create/modify/rename/delete/set-current. Refusals are decided before the
undo step is recorded. Python wrapper, real-IPC audit with DWG/DXF persistence,
IPC round-trip test, Python unit test and docs.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>