WebKit: Dashboard-tree row Tab-order lands on INPUT/BODY, not pencil/menu

The gap

tests/e2e/dashboard-tree.spec.js:316 — "Tab walks the row, its chevron and its
trailing actions, each ringed differently" — fails on WebKit on current main
(434643e, the tip after PR #495/#493), independent of any change on this branch.

Expected: ["workspace:sales", "chevron", "pencil", "menu"]
Received: ["workspace:sales", "chevron", "INPUT", "BODY"]

Tab-focus lands on INPUT/BODY instead of the row's pencil/menu trailing
actions on WebKit only; chromium passes the same spec. Reproduced twice,
deterministically (not a timing flake):

npx playwright install chromium webkit   # browsers were not preinstalled
npm run test:e2e -- --project=webkit -g "Tab walks the row"

Why deferred

Surfaced while shipping #466 (tab-close unsaved-change guard), which never
touches dashboard-tree.ts, dialog-shell.ts, or focus/tab-order code.
Confirmed present on a clean main checkout (stashed #466's changes, reran —
same failure), so it predates and is unrelated to that work. Likely connected
to the #429 phase 3 rename-pencil trailing action recently added to the row
(the expected order names pencil/menu — the two newest trailing actions).

Also worth noting for whoever picks this up: CI does not run test:e2e on a
PR (chromium/webkit only run locally), so this has had no green/red signal
since #429 phase 3 merged.

Start with tests/e2e/dashboard-tree.spec.js:316 and reproduce the failure using the provided WebKit Playwright command. Then inspect dashboard-tree.ts, dialog-shell.ts, and the focus/tab-order code, with the goal that WebKit reports the row, chevron, pencil, and menu sequence without INPUT or BODY.