Clear scroll-to-citation `setTimeout`s on panel close/unmount in source-detail-panel

[MODSetter]

Description

In source-detail-panel.tsx, when opening the panel to a cited chunk, multiple setTimeouts are fired at staggered delays (50ms, 150ms, 300ms, 600ms, 1000ms) to scroll to the cited chunk. None of these are tracked or cleared — if the user closes the panel before all fire, setHasScrolledToCited and setActiveChunkIndex are called on a closed/unmounted panel.

File to change

• surfsense_web/components/new-chat/source-detail-panel.tsx (lines 230-245)

Current code

const scrollAttempts = [50, 150, 300, 600, 1000];
scrollAttempts.forEach((delay) => {
  setTimeout(() => { scrollToCitedChunk(); }, delay);
});
setTimeout(() => {
  setHasScrolledToCited(true);
  setActiveChunkIndex(citedChunkIndex);
}, scrollAttempts[scrollAttempts.length - 1] + 50);

What to do

1. Store timeout IDs in a ref: const scrollTimersRef = useRef<ReturnType<typeof setTimeout>[]>([]);
2. Push each setTimeout return value into scrollTimersRef.current
3. Clear all timers when open becomes false or on unmount:

useEffect(() => {
  if (!open) {
    scrollTimersRef.current.forEach(clearTimeout);
    scrollTimersRef.current = [];
  }
  return () => {
    scrollTimersRef.current.forEach(clearTimeout);
    scrollTimersRef.current = [];
  };
}, [open]);

Acceptance criteria

• All scroll timeouts are cleared when the panel closes or unmounts
• Scroll-to-cited-chunk still works when panel stays open