fix(editor): support copying single image from edgeless and pasting to page (#12709)

Closes: [BS-3586](https://linear.app/affine-design/issue/BS-3586/复制白板图片，然后粘贴到-page，图片失败)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Copying a single selected image in edgeless mode now places the image directly onto the system clipboard as a native image blob for smoother pasting.

- **Bug Fixes**
  - Enhanced clipboard handling to better manage image and text data inclusion, with improved fallback for snapshot HTML.

- **Tests**
  - Added an end-to-end test verifying image copy-paste functionality between edgeless and page editor modes.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/utils/clipboard/index.ts

@@ -34,12 +34,12 @@ export const copyLinkToBlockStdScopeClipboard = async (
 
   if (clipboardWriteIsSupported) {
     try {
-      await clipboard.writeToClipboard(items => {
-        items['text/plain'] = text;
+      await clipboard.writeToClipboard(items => ({
+        ...items,
+        'text/plain': text,
         // wrap a link
-        items['text/html'] = `<a href="${text}">${text}</a>`;
-        return items;
-      });
+        'text/html': `<a href="${text}">${text}</a>`,
+      }));
       success = true;
     } catch (error) {
       console.error(error);