The Arcturus errors "page hierarchy contains a cycle page 354 and 357" and
"sibling order 1 is used more than once (111 problems)" come from
catalog_pages, not catalog_items: pages 354/357 point at themselves, and
many parents have child pages sharing the same order_num. Extend the
emulator catalog scan + fix to detect both: pages whose parent chain loops
back get detached (parent_id = 0 on the highest cycle member) and every
affected parent's children are renumbered sequentially, preserving their
current relative order.
Add scripts/diag-emulator.ts to inspect the live catalog state.
