Which solutions provide this?
The Gantt support needs to support auto-dependency "links" between tasks. (There are tools that support a Gantt layout but with no auto-task-dependency management--eg: monday.com--but that's insufficient for my requirements.)
My initial research has not yet found anything. I've looked at several tools, but I'm far from completing a comprehensive search. Microsoft Project appears to support PERT charts, but to what extent it can do the above is currently unclear. At this point, I'm not optimistic I'll find anything, but I'm early in my search.
EDIT: WBS Schedule Pro shows some initial promise.