40337e9c18
Review feedback on #4359: the copy affordance sat inside a tooltip trigger that forced tabIndex -1, so keyboard users could not reach it; pass tabbable through. The default-alerts seed could also complete its write after the 5s timeout fired and overwrite a user's first alert edit; the timeout now aborts the seed before it writes. A fully atomic create-if-absent needs a platform API change and is out of scope here.