fix: zoom in/out click

[marvin-season]

Summary

Optimize the user experience in the workflow for zooming in and out. When zoomed to 200% or 25%, the zoom buttons are disabled, and the cursor changes to indicate a disabled state.

Screenshots

Before: There is no disabled click style applied.

After:

Checklist

• 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