fix(web/m7-352): use typographic apostrophe in failed-variant copy

web/src/lib/components/PlaylistPlaceholderCard.svelte

@@ -14,7 +14,7 @@
   const copy = $derived.by(() => {
     switch (variant) {
       case 'building':    return 'Building your daily mix…';
-      case 'failed':      return 'Couldn't build this mix. Retrying soon.';
+      case 'failed':      return 'Couldn’t build this mix. Retrying soon.';
       case 'seed-needed': return 'Listen to more variety to unlock this slot.';
       default:            return 'Listen to a few tracks — appears within 24h.';
     }

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

@@ -17,7 +17,7 @@ describe('PlaylistPlaceholderCard', () => {
 
   test('failed variant shows failure copy and does NOT pulse', () => {
     const { container } = render(PlaylistPlaceholderCard, { props: { label: 'For You', variant: 'failed' } });
-    expect(screen.getByText(/Couldn't build this mix/i)).toBeInTheDocument();
+    expect(screen.getByText(/Couldn.t build this mix/i)).toBeInTheDocument();
     const cover = container.querySelector('[data-variant="failed"] .aspect-square');
     expect(cover?.className).not.toMatch(/animate-pulse/);
   });