Regenerate the gesture vocabulary over the library work

`Traceability` stayed red after the matrix was regenerated, on its other
gate: `gestures-check`. Same cause, second artefact. `docs/gestures.md`
cites each gesture by `file:LINE`, and the library UI work moved the two
selection-mode gestures down a hundred lines — 3923 -> 4032 and
3940 -> 4049 in `ui/dr-ui/ui/library.slint`. Nothing about the gestures
themselves changed.

`ui/dr-ui/src/gesture_book.rs` was already current, so this is the doc
alone: 70 files scanned, 16 gestures, 2 places, gate PASS.

Worth knowing for next time: `tools/ci-local.sh traceability` runs the
self-test, the coverage gate and the matrix, but not `gestures-check`, so a
clean local run does not prove this workflow green.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/gestures.md

@@ -144,7 +144,7 @@ A star has to take the press without it also reaching the cell, or every rating
 
 Distinct from Done, which leaves the mode entirely. Clearing keeps it, so the next selection can start straight away.
 
-<sub>`ui/dr-ui/ui/library.slint:3923`</sub>
+<sub>`ui/dr-ui/ui/library.slint:4032`</sub>
 
 ### Select everything the grid is showing
 
@@ -153,4 +153,4 @@ Distinct from Done, which leaves the mode entirely. Clearing keeps it, so the ne
 
 A scoped grid of two hundred frames is two hundred taps otherwise, and "all of them, except those three" is a far more common shape than the taps it took to say it.
 
-<sub>`ui/dr-ui/ui/library.slint:3940`</sub>
+<sub>`ui/dr-ui/ui/library.slint:4049`</sub>