Output of createTabOverflowTemplateBindings. Carries the two
resolved templates plus a stable trigger-context signal and an
imperative item-context builder.
ActiveDescendantItem[] projection of hiddenTabs() for
CngxActiveDescendant.items. Each entry's id matches the
row's <li> (see tabOverflowOptionId); value carries
the tab handle so AD's (activated) payload casts back without
a registry lookup. Structural equal guards against no-op IO
cascades. Mutable array shape because CngxActiveDescendant.items declares the input that way; the
array is rebuilt each computed run so callers can't mutate the
live source.