code improve

src/composables/useCopy.ts

@@ -25,7 +25,9 @@ export const useCopy = () => {
       const serializedData = canvas.copyToClipboard()
       // Use TextEncoder to handle Unicode characters properly
       const base64Data = btoa(
-        String.fromCharCode(...new TextEncoder().encode(serializedData))
+        String.fromCharCode(
+          ...Array.from(new TextEncoder().encode(serializedData))
+        )
       )
       // clearData doesn't remove images from clipboard
       e.clipboardData?.setData(

tests-ui/tests/composables/clipboard.test.ts

@@ -4,7 +4,9 @@ import { describe, expect, it } from 'vitest'
  * Encodes a UTF-8 string to base64 (same logic as useCopy.ts)
  */
 function encodeClipboardData(data: string): string {
-  return btoa(String.fromCharCode(...new TextEncoder().encode(data)))
+  return btoa(
+    String.fromCharCode(...Array.from(new TextEncoder().encode(data)))
+  )
 }
 
 /**