feat: add notes app

layers/notes/app/components/NotesSidebarHandle.vue

@@ -0,0 +1,25 @@
+<script setup lang="ts">
+// Desktop only: a chevron on the sidebar's right border (or the window's left edge when the
+// sidebar is hidden) that appears on hover and shows/hides the note list
+const { open, toggle } = useNotesSidebar()
+</script>
+
+<template>
+  <!-- The whole hover area is the button. It only reaches to the right of the line (never over the note list's
+       delete buttons), as wide as the note's side padding (md:px-10), so it never covers the text either -->
+  <button
+    type="button"
+    :title="`${open ? 'Hide' : 'Show'} notes (⌘E)`"
+    :aria-label="open ? 'Hide notes' : 'Show notes'"
+    class="group fixed inset-y-0 z-20 hidden w-10 cursor-pointer items-center focus:outline-none md:flex"
+    :class="open ? 'left-72' : 'left-0'"
+    @click="toggle"
+  >
+    <span
+      class="flex size-6 items-center justify-center rounded-full bg-default text-muted opacity-0 shadow-sm ring-1 ring-accented transition-opacity group-hover:opacity-100 group-focus-visible:opacity-100 group-focus-visible:ring-2 group-focus-visible:ring-primary"
+      :class="open ? '-translate-x-1/2' : 'ms-2'"
+    >
+      <UIcon :name="open ? 'i-lucide-chevron-left' : 'i-lucide-chevron-right'" class="size-4" />
+    </span>
+  </button>
+</template>