Upstream's shift+enter summarize-and-switch test file (f33465a97, brought in
by the upstream/main merge) asserts navigateTree's options literally, but
this PR's ask-reanswer flow always passes allowAskReopen: true. Update the
NavigateTree mock type and the four call assertions to match.
- Shift+Enter on a tree entry forks with a branch summary directly, skipping
the summary prompt and ignoring the branchSummary.enabled gate.
- Plain Enter keeps existing behavior: direct switch, with the summary prompt
only for users who enabled branchSummary.enabled.
- Updated the selector help line and added controller-level regression tests.
Fixes#5152
Mathews-Tom