fix(layout): prevent document-level scroll-y when stacked notes overflow

Contain horizontal overflow within #main-app instead of leaking to the
document, which caused a horizontal scrollbar to consume viewport height
and trigger an unwanted vertical scrollbar. Also fix note pane height
to use 100% instead of 100vh, and switch useResizeContainer to minWidth
so the flex container can grow when the window is wider than the notes.
Add a window resize listener to keep the value accurate on resize.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/hooks/useResizeContainer.hook.ts

@@ -1,4 +1,4 @@
-import { onMounted, type Ref, watch } from "vue"
+import { onMounted, onUnmounted, type Ref, watch } from "vue"
 
 import { getNoteWidth } from "@/constants/note-width"
 import { useOverlay } from "@/hooks/useOverlay.hook"
@@ -21,7 +21,7 @@ export const useResizeContainer = (
     if (isMobile.value) {
       container.style.height = `${(stackedNotes.value.length + 1) * 100}vh`
     } else {
-      container.style.width = `${
+      container.style.minWidth = `${
         getNoteWidth() * (stackedNotes.value.length + 1)
       }px`
     }
@@ -29,6 +29,11 @@ export const useResizeContainer = (
 
   onMounted(() => {
     resizeContainer()
+    window.addEventListener("resize", resizeContainer)
+  })
+
+  onUnmounted(() => {
+    window.removeEventListener("resize", resizeContainer)
   })
 
   watch(stackedNotes, resizeContainer, {