Send typing events on keyup, not on focus

Editor assessment

The subject is precise and includes its own contrast: typing events are sent on keyup rather than on focus, and any reader understands both the defect, typing indicators firing for anyone who merely focused the field, and the remedy, without the diff. Chore is a defensible type for event timing even though fix could fit; the straddle is arguable. The trailing pull-request number is the conventional squash-merge marker. No body is needed for a change this self-describing. Hygiene is good: imperative, no trailing period, no junk. A tidy, publishable message.