tabs is the presenter's live handle list - the action receives the
target index, so it needs the registry to resolve the matching
CngxTabHandle before computing its route. [cngxTabsRouteSync]
passes the host's tabs signal straight through.
Maps a tab handle to its router command array. Default
(handle) => [handle.id] - the tab id is the child segment.
Override for real route paths ((h) => ['settings', h.id]).