fix(ui-tui): clear sticky prompt when follow snaps to bottom

Renderer-driven follow-to-bottom was restoring the viewport to the tail without notifying ScrollBox subscribers, so StickyPromptTracker could stay stale-visible. Notify on render-time scroll/sticky changes and treat near-bottom as bottom for prompt hiding.

ui-tui/packages/hermes-ink/src/ink/dom.ts

@@ -72,6 +72,7 @@ export type DOMElement = {
   scrollViewportHeight?: number
   scrollViewportTop?: number
   stickyScroll?: boolean
+  notifyScrollChange?: () => void
   // Set by ScrollBox.scrollToElement; render-node-to-output reads
   // el.yogaNode.getComputedTop() (FRESH — same Yoga pass as scrollHeight)
   // and sets scrollTop = top + offset, then clears this. Unlike an