refactor: enhance modal layouts and scrolling behavior across components

[CodingOnStar]

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Summary

• Updated various modal components to improve layout and scrolling behavior, ensuring content is properly contained and scrollable.
• Adjusted CSS classes for better responsiveness and visual consistency.
• Added tests to verify scrolling functionality within the ConfigModal.

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 make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.82%. Comparing base (1aa6188) to head (369fbe4).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #36033   +/-   ##
=======================================
  Coverage   85.82%   85.82%           
=======================================
  Files        4453     4453           
  Lines      209954   209963    +9     
  Branches    39350    39353    +3     
=======================================
+ Hits       180190   180201   +11     
+ Misses      26551    26549    -2     
  Partials     3213     3213           

Flag	Coverage Δ
dify-ui	94.40% <ø> (ø)
web	86.62% <100.00%> (+<0.01%)	⬆️

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