Round 1: Fix updateCommandRow offset, structTypeName undo, changeNodeKind
macro, shift-click kCommandRowId leak, type filter byte-vs-column bug.
Round 2: Move kFooterIdBit to core.h, add RcxEditor destructor for cursor
cleanup, defer refresh during batch ops, use newline separator in type
picker, narrow selection on double-click edit, clear hover on keyboard
scroll, guard 0x prefix from deletion, cap array count at 100k.