feat(web/m7-364): drawer focus management + grip Enter/Space handling

web/src/lib/components/QueueDrawer.svelte

@@ -3,12 +3,27 @@
   import { player, closeQueueDrawer } from '$lib/player/store.svelte';
   import QueueTrackRow from './QueueTrackRow.svelte';
 
+  let previouslyFocused: HTMLElement | null = null;
+  let closeButton: HTMLButtonElement | undefined = $state();
+
   function totalDurationLabel(tracks: { duration_sec: number }[]): string {
     const totalSec = tracks.reduce((s, tr) => s + (tr.duration_sec ?? 0), 0);
     const m = Math.floor(totalSec / 60);
     const h = Math.floor(m / 60);
     return h > 0 ? `${h}h ${m % 60}m` : `${m} min`;
   }
+
+  $effect(() => {
+    if (player.queueDrawerOpen) {
+      previouslyFocused = document.activeElement as HTMLElement | null;
+      // Defer to next microtask so the close button is rendered + visible
+      // before we focus (the drawer may still be transitioning in).
+      Promise.resolve().then(() => closeButton?.focus());
+    } else if (previouslyFocused) {
+      previouslyFocused.focus();
+      previouslyFocused = null;
+    }
+  });
 </script>
 
 {#if player.queueDrawerOpen}
@@ -38,6 +53,7 @@
     </div>
     <button
       type="button"
+      bind:this={closeButton}
       aria-label="Close queue"
       onclick={() => closeQueueDrawer()}
       class="text-text-secondary hover:text-text-primary"