fix(workflow): correct edge type mapping typo

[stonexer]

Summary

This PR updates the mapping of custom edge types in the workflow component. The change involves replacing the key from CUSTOM_NODE to CUSTOM_EDGE in the edgeTypes object within app/components/workflow/index.tsx.

Screenshots

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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

[crazywoola]

Thanks for the contribution, please open an issue or link an existing issue in description.

[stonexer]

Thanks for the contribution, please open an issue or link an existing issue in description.

Sorry, this is just fixing a possible variable name typo and does not correspond to an issue.