Previously, tab selection for direct-linked annotations was happening
before anchoring was complete—that means that orphaned annotations had
not yet been marked as being orphans (`$orphan`). Make sure that
direct-linked tab selection is checked any time the direct-linked
annotation changes.

Also fix a UI confusion in which the "Show All" button would show
the count of all annotations in this (direct-linked) state, which is
confusing because orphans don't count toward "All annotations" (nor do
page notes, FWIW).

Fixes #2686