m4: mobile nav — hamburger + slide-in drawer

Below sm the sidebar had no replacement (nav was inaccessible on phones).
The sidebar aside is now a responsive drawer: fixed + off-canvas with a
hamburger toggle and backdrop on mobile, static in-flow on sm+ (same markup,
no duplication). Closes on nav-click, backdrop, Esc, or route change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

frontend/src/components/AppShell.vue

@@ -21,6 +21,7 @@ const ui = useUiStore();
 const managing = ref(false);
 const showShortcuts = ref(false);
 const paletteOpen = ref(false);
+const drawer = ref(false);
 const searchInput = ref<HTMLInputElement | null>(null);
 const searchText = ref(typeof route.query.q === "string" ? route.query.q : "");
 let searchTimer: ReturnType<typeof setTimeout> | undefined;
@@ -79,6 +80,10 @@ function onKeydown(e: KeyboardEvent) {
     showShortcuts.value = false;
     return;
   }
+  if (e.key === "Escape" && drawer.value) {
+    drawer.value = false;
+    return;
+  }
   if (e.metaKey || e.ctrlKey || e.altKey) return;
   if (gPending) {
     gPending = false;
@@ -148,6 +153,7 @@ watch(
   () => route.name,
   (name) => {
     if (name !== "search") searchText.value = "";
+    drawer.value = false;
   },
 );
 
@@ -163,6 +169,26 @@ async function signOut() {
       class="sticky top-0 z-20 border-b border-neutral-200 bg-neutral-50/90 backdrop-blur dark:border-neutral-800 dark:bg-neutral-950/90"
     >
       <div class="flex items-center gap-3 px-4 py-3">
+        <button
+          type="button"
+          class="icon-btn sm:hidden"
+          title="Menu"
+          aria-label="Open menu"
+          @click="drawer = true"
+        >
+          <svg
+            class="h-5 w-5"
+            viewBox="0 0 24 24"
+            fill="none"
+            stroke="currentColor"
+            stroke-width="2"
+            stroke-linecap="round"
+          >
+            <line x1="3" y1="6" x2="21" y2="6" />
+            <line x1="3" y1="12" x2="21" y2="12" />
+            <line x1="3" y1="18" x2="21" y2="18" />
+          </svg>
+        </button>
         <div class="flex shrink-0 items-center gap-2">
           <div class="flex h-8 w-8 items-center justify-center rounded-lg bg-brand text-sm font-black text-neutral-900">
             TS
@@ -203,8 +229,17 @@ async function signOut() {
     </header>
 
     <div class="flex flex-1">
-      <aside class="hidden w-56 shrink-0 border-r border-neutral-200 p-3 sm:block dark:border-neutral-800">
-        <nav class="flex flex-col gap-0.5 text-sm">
+      <div
+        v-if="drawer"
+        class="fixed inset-0 z-30 bg-black/40 sm:hidden"
+        aria-hidden="true"
+        @click="drawer = false"
+      ></div>
+      <aside
+        class="fixed inset-y-0 left-0 z-40 w-64 -translate-x-full overflow-y-auto border-r border-neutral-200 bg-neutral-50 p-3 transition-transform duration-200 sm:static sm:z-auto sm:w-56 sm:translate-x-0 dark:border-neutral-800 dark:bg-neutral-950"
+        :class="drawer ? 'translate-x-0' : ''"
+      >
+        <nav class="flex flex-col gap-0.5 text-sm" @click="drawer = false">
           <RouterLink to="/" class="nav-link" :class="route.name === 'board' ? 'nav-link-active' : ''">
             <Icon name="note" /> Notes
           </RouterLink>