fix(project): race-safe batch scene preview import and close

Serialize updateProject and preview finalize, drain before pack/close, buffer zip entries, and abort finalize cleanly when leaving the project to avoid ENOENT on multi-image drops.

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

app/main/project/scenePreviewThumbnail.test.ts

@@ -33,3 +33,19 @@ void test('generateScenePreviewThumbnailBytes: image scales to max edge', async
 
   await fs.rm(tmp, { recursive: true, force: true });
 });
+
+void test('generateScenePreviewThumbnailBytes: accepts image Buffer', async () => {
+  const png = await sharp({
+    create: {
+      width: 120,
+      height: 80,
+      channels: 3,
+      background: { r: 10, g: 20, b: 30 },
+    },
+  })
+    .png()
+    .toBuffer();
+  const buf = await generateScenePreviewThumbnailBytes(png, 'image');
+  assert.ok(buf !== null);
+  assert.ok(buf.length > 0);
+});