refactor(notes): restore fixed mobile heights for scroll math

Re-pin .note and .stacked-note to 100dvh on mobile and bring back the
container height in useResizeContainer so (index + 1) * height has a
reachable scroll target. Switch the polled scroll helper to that same
formula instead of offsetTop.

src/hooks/useResizeContainer.hook.ts

@@ -18,7 +18,9 @@ export const useResizeContainer = (
       return
     }
 
-    if (!isMobile.value) {
+    if (isMobile.value) {
+      container.style.height = `${(stackedNotes.value.length + 1) * 100}dvh`
+    } else {
       container.style.minWidth = `${
         getNoteWidth() * (stackedNotes.value.length + 1)
       }px`