[PATCH RFC 0/2] review-tui: add a "cherry-pick + merge" take method

The review TUI's Take dialog can apply a series three ways: merge (a
cover-letter merge commit of the whole series), linear (git am onto the
target branch), or cherry-pick (pick a subset and git am it). It could
not do the combination a maintainer often wants: take a hand-picked
subset of a series *and* record it as a cover-letter merge commit -- the
equivalent of "b4 shazam -M -P".

That path was already half-wired. When some patches were marked skipped,
the "merge" method fell through to the patch picker and merged just the
non-skipped patches -- _do_take_merge already builds its mbox from a
cherry-pick selection. But with nothing pre-skipped there was no way to
ask for it: "merge" always took the whole series.

This series turns it into a first-class choice. A new method,
"cherry-pick + merge" (merge-pick), always opens the patch picker like
cherry-pick and then routes through the merge path like merge:

  - _on_take_confirmed always shows the picker for merge-pick;
  - _on_take_final dispatches it to _do_take_merge;
  - the apply self-test bases it at the series base-commit, like merge;
  - it is accepted as a b4.review-default-take-method value.

The picker's existing pre-deselection of skipped patches is reused, so
cherry-pick + merge over a series that has skips starts with those
patches deselected, like the other picker paths.

Patch 1 adds the method and updates the docs; patch 2 extends
TestMergeTakeSkipRouting to cover the new routing -- the picker always
opens, the chosen method survives the picker, and the final dispatch
lands on _do_take_merge rather than git am.

ci.sh checkers (ruff format/check, ty) are clean on the changed sources,
and the tui-tracking, tui-modals, tui-review, and three-way-merge suites
pass (213 tests).

Signed-off-by: Christian Brauner (Amutable) <[email protected]>
---
Christian Brauner (2):
      review-tui: add cherry-pick+merge take method
      review-tui: test the cherry-pick+merge take method

 docs/config.rst                    |  5 +--
 docs/releases.rst                  | 10 ++++++
 docs/reviewer/getting-started.rst  |  6 ++--
 src/b4/review_tui/_modals.py       |  7 ++--
 src/b4/review_tui/_tracking_app.py | 26 ++++++++-------
 src/tests/test_tui_tracking.py     | 66 ++++++++++++++++++++++++++++++++++++++
 6 files changed, 102 insertions(+), 18 deletions(-)
---
base-commit: 0a1954d329ab57f7aab40743fad7dc6e3c45d35d
change-id: 20260625-20260625-review-tui-take-cherry-pick-merge-38a536bdb1fc