fix(settings): adds hysteresis to header scroll threshold

Shrink at scrollY > 50, expand only at scrollY < 10. The 40px dead
zone absorbs the ~32px content shift from header padding change,
preventing the layout feedback loop where header resize triggers
scroll position change which re-triggers header resize.

Author: wgordon17

src/app/components/settings/SettingsPage.tsx

@@ -84,7 +84,9 @@ export default function SettingsPage() {
   onMount(() => {
     const onScroll = () => {
       if (document.documentElement.dataset.scrollLock) return;
-      setScrolled(window.scrollY > 50);
+      const y = window.scrollY;
+      if (scrolled() && y < 10) setScrolled(false);
+      else if (!scrolled() && y > 50) setScrolled(true);
     };
     window.addEventListener("scroll", onScroll, { passive: true });
     onCleanup(() => window.removeEventListener("scroll", onScroll));