fix(web/m7-364): vitest failures — exact-match query, inert prop, -0, user guard

CI test-web was blocking on:

- QueueDrawer.test close-button query: getByLabelText(/close queue/i)
  matched BOTH the backdrop button (aria-label="Close queue backdrop")
  and the close button (aria-label="Close queue"). Switched to exact
  string match.

- QueueDrawer.test inert assertion: Svelte 5 + jsdom uses property
  binding for `inert`, not attribute, so hasAttribute('inert') returns
  false. Check the DOM property (with attribute fallback for
  robustness) instead.

- queue-row-math.ts -0 normalization: Math.round(-0.5) returns -0,
  and Object.is(-0, 0) is false — vitest's .toBe(0) fails. Added
  `|| 0` to normalize -0 to +0 at the function boundary so consumers
  never see -0.

- player/store.svelte.ts user import guard: persistence $effect.root
  reads `user.value?.id` at module-init, but in test files where
  auth/store.svelte.ts is imported transitively (auth/store.test,
  playlists/playlists.test), the player module loads via auth's
  import chain before auth's `user` binding is assigned. `user?.value`
  guards against that init-order race. The proper fix is to invert
  the auth↔player import dep (filed as I2 follow-up under #375).

web/src/lib/components/QueueDrawer.test.ts

@@ -63,7 +63,7 @@ describe('QueueDrawer', () => {
 
   it('clicking the close button calls closeQueueDrawer', async () => {
     render(QueueDrawer);
-    const close = screen.getByLabelText(/close queue/i);
+    const close = screen.getByLabelText('Close queue');
     await fireEvent.click(close);
     expect(closeQueueDrawer).toHaveBeenCalled();
   });
@@ -84,12 +84,16 @@ describe('QueueDrawer', () => {
     expect(aside!.getAttribute('aria-hidden')).toBe('true');
   });
 
-  it('drawer has inert attribute when closed', () => {
+  it('drawer is inert when closed', () => {
     openValue = false;
     queueValue = [t('a')];
     render(QueueDrawer);
     const aside = document.querySelector('aside[aria-label="Playback queue"]');
     expect(aside).not.toBeNull();
-    expect(aside!.hasAttribute('inert')).toBe(true);
+    // Svelte 5 + jsdom uses property binding for `inert`, not attribute. Check both
+    // to be robust regardless of which jsdom version handles the mirror.
+    const inertProp = (aside as unknown as { inert?: boolean }).inert === true;
+    const inertAttr = aside!.hasAttribute('inert');
+    expect(inertProp || inertAttr).toBe(true);
   });
 });

web/src/lib/components/queue-row-math.ts

@@ -4,5 +4,7 @@
 // the user's drop intent maps to a clean queue index.
 export function offsetToDelta(offsetY: number, rowHeight: number): number {
   if (rowHeight <= 0) return 0;
-  return Math.round(offsetY / rowHeight);
+  // `|| 0` normalizes -0 to +0. Math.round(-0.5) === -0; downstream
+  // consumers (and Object.is in tests) treat -0 and +0 as distinct.
+  return Math.round(offsetY / rowHeight) || 0;
 }

web/src/lib/player/store.svelte.ts

@@ -397,7 +397,10 @@ $effect.root(() => {
   // queue/index changes drive it. The throttled-write effect below
   // covers position drift.
   $effect(() => {
-    const userId = user.value?.id;
+    // `user?.value` (not `user.value`) guards against module-init order during
+    // tests: auth/store.svelte.ts imports from this file, so when this module
+    // loads via that chain, `user` may not yet be assigned. See I2 follow-up.
+    const userId = user?.value?.id;
     if (!userId) return;
     // Reading these registers the reactive dependency; the values
     // themselves are unused — writePersistedQueue re-reads live state.
@@ -413,7 +416,7 @@ $effect.root(() => {
 
   // Throttled write on position changes.
   $effect(() => {
-    const userId = user.value?.id;
+    const userId = user?.value?.id;
     if (!userId) return;
     const _p = _position;
     void _p;