fix: post-smoke-test polish — preserve playhead, clip list redesign, play-clip action, 1100x750 default

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/components/Timeline.svelte

@@ -279,6 +279,15 @@
       case 'delete-clip':
         if (clipStore.selectedClipId) removeClip(clipStore.selectedClipId);
         break;
+      case 'play-clip': {
+        const clip = clipStore.clips.find((c) => c.id === clipStore.selectedClipId);
+        if (clip) {
+          seekTo(clip.startTime);
+          const videoEl = document.querySelector('video');
+          if (videoEl?.paused) videoEl.play();
+        }
+        break;
+      }
       default: {
         const _exhaustive: never = action;
         void _exhaustive;