fix: cannot close notification manually

[xuzuodong]

Summary

Fixed the issue where the notification could not be closed manually. Additionally, to prevent potential memory leaks, ensured that the Toast component is properly unmounted on close.

Screenshots

Before	After
2024-12-09.16.26.08.mov	2024-12-09.16.26.37.mov

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods