fix(web): guard ChatPane scroll setState to prevent Maximum update depth error (#3187)

The scroll handler in ChatPane called setScrolledFromBottom on every
scroll event. During streaming, programmatic scrollTop assignments
(followLatestIfPinned via rAF + ResizeObserver) emit synchronous scroll
events while React is still committing prior updates, scheduling a
setState per tick. React eventually trips its update-depth guard with
'Maximum update depth exceeded' (issue surfaces in Next.js 16
Turbopack dev consoles).

Use a functional updater that returns prev when the boolean is
unchanged so React skips the re-render entirely. This breaks the
cascade at the call site without touching the auto-follow logic.

Co-authored-by: nicejames <nicejames@gmail.com>

apps/web/src/components/ChatPane.tsx

@@ -658,7 +658,12 @@ export function ChatPane({
       snapshot(target);
       const distance =
         target.scrollHeight - target.scrollTop - target.clientHeight;
-      setScrolledFromBottom(distance > 120);
+      // Functional updater bails out when the value is unchanged so a flood
+      // of scroll events (e.g. programmatic scrollTop + ResizeObserver
+      // follow-up during streaming) does not schedule a re-render per tick
+      // and trip React's "Maximum update depth exceeded" guard.
+      const next = distance > 120;
+      setScrolledFromBottom((prev) => (prev === next ? prev : next));
       pinnedToBottomRef.current = distance < 80;
     }
     el.addEventListener('scroll', onScroll);