fix(web/m7-364): TrackRef field shape + seek-on-restore + drawer inert

CI svelte-check failed on 5 type errors caused by the slice using
duration_ms/album_name fields that don't exist on TrackRef (the real
shape uses duration_sec + album_id/album_title). Fixed across
QueueDrawer, QueueDrawer.test, QueueTrackRow.test, persisted.test,
and the inline `state.current = null` in PlayerBar.test (TrackRef |
undefined, not | null).

Final whole-slice review concerns also rolled in:

- C1 (Critical): persisted position was restored to UI but never
  seeked into the audio element — first timeupdate snapped _position
  back to 0. Added a one-shot _pendingRestorePosition module ref +
  consumePendingRestorePosition() export; layout's loadedmetadata
  handler now seeks once on restore.

- I1 (Important): throttled-write effect now wraps _queue / _index
  reads in untrack so the dependency tracking matches the design
  intent. Position remains the only tracked dep.

- I4 (Important): drawer gets inert={!queueDrawerOpen} so its inner
  buttons drop out of tab order when closed (aria-hidden alone
  doesn't do that). Removed redundant role="complementary" from
  <aside> (implied by the element). New test asserts inert binding.

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

web/src/routes/+layout.svelte

@@ -13,7 +13,8 @@
     reportDuration,
     reportStateFromAudio,
     player,
-    closeQueueDrawer
+    closeQueueDrawer,
+    consumePendingRestorePosition
   } from '$lib/player/store.svelte';
   import { useMediaSession } from '$lib/player/mediaSession.svelte';
   import { useEventsDispatcher } from '$lib/player/events.svelte';
@@ -86,7 +87,14 @@
   bind:this={audioEl}
   preload="metadata"
   ontimeupdate={() => audioEl && reportTimeUpdate(audioEl.currentTime)}
-  onloadedmetadata={() => audioEl && reportDuration(audioEl.duration)}
+  onloadedmetadata={() => {
+    if (!audioEl) return;
+    reportDuration(audioEl.duration);
+    const restorePos = consumePendingRestorePosition();
+    if (restorePos !== null) {
+      audioEl.currentTime = restorePos;
+    }
+  }}
   onplaying={() => reportStateFromAudio('playing')}
   onpause={() => reportStateFromAudio('paused')}
   onwaiting={() => reportStateFromAudio('waiting')}