[woksin]

Fixed

• Navigation toolbar buttons now carry their title as an explicit aria-label, so an icon-only button in a compact topbar or slim rail is announced by name (Toolbar buttons with an icon and secondary emphasis draw no label and have no accessible name #254)

[woksin]

Notes for reviewers

• Scope: Toolbar buttons with an icon and secondary emphasis draw no label and have no accessible name #254. Since v4.78.6 (21114f2) the toolbar button has its title as tooltip and accessible name. This PR adds the explicit aria-label that the issue asks for, plus a spec assertion.
• Out of scope, by design: compact topbar and slim rail layouts hide button labels and the application name. That's a layout choice.
• Local checks: whole-repo JS build, Source/JavaScript/react specs and lint (lint:ci) all pass. The remaining yarn ci workspaces, browser shards and .NET specs run in CI.
• Review: quick review round, passed, no findings. Assigned to woksin; this PR is authored as woksin, so no review request.