Extract the repeated `setTimeout(() => …close…, 0)` overlay/prompt-close
pattern into a single `deferClose(fn)` helper (src/logic/defer.ts) so the
"why deferred" rationale (let the closing keystroke finish dispatching before
the composer remounts/refocuses) lives in one place.
Rewires the 5 close-defer sites: closePager/closeDashboard/closeSwitcher/
closePicker in view/App.tsx and clearSoon in view/prompts/promptOverlay.tsx.
Timing is unchanged (0ms). Other setTimeout uses (quit window, flashHint,
scroll re-anchor, resize debounce, transport) are NOT close-defers and are
left untouched.
b36001940a