fix: Add pixel tolerance to audio widget test for stability

- Add maxDiffPixels: 50 to allow minor rendering variations
- Prevents flaky test failures from insignificant pixel differences (< 0.01%)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

browser_tests/tests/widget.spec.ts

@@ -313,7 +313,9 @@ test.describe('Load audio widget', () => {
   test('Can load audio', async ({ comfyPage }) => {
     await comfyPage.loadWorkflow('widgets/load_audio_widget')
     await comfyPage.page.waitForTimeout(500)
-    await expect(comfyPage.canvas).toHaveScreenshot('load_audio_widget.png')
+    await expect(comfyPage.canvas).toHaveScreenshot('load_audio_widget.png', {
+      maxDiffPixels: 50
+    })
   })
 })