bugfix: db insert error when notion page_name too long

[xlight]

fix the bug:
SQL error cause by page_name too long when Sync Notion pages #14314

Summary

Truncate page name to 255 characters to prevent DB field length errors
Fixes #<14314>

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