fix(datasets): add created_by to ApiToken for get datasets from api correct current user

[hgbdev]

Summary

This PR Fixes #11331. The problem was that admin-created API keys always showed the owner’s dataset list, even when the owner set “Only Me” permissions.

I added a new field, created_by, to the ApiToken model to track who created each API key. This makes sure the correct user and permissions are used when accessing datasets.

In the web console, users will now only see the Datasets API keys they created. Old keys without the created_by field will still work fine.

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