fix: fix evaluator config dialog layout

[yfrigui2]

Adjust styling of evaluator config dialog to handle overflows

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Note

Add truncation and overflow handling to evaluator dialog title and dataset select button, plus spacing tweaks in dialog header.

• Evaluator Config Dialog (EvaluatorConfigDialog.tsx):
  • Wrap title sections with overflow: hidden and use Truncate for evaluator.name and dataset.name.
  • Adjust title layout with Flex props (maxWidth, flexBasis, minWidth) to prevent overflow.
• Dataset Picker (DatasetSelectWithSplits.tsx):
  • Add overflow: hidden to button content and use Truncate for dataset and split text.
  • Refactor split label rendering within Text using Truncate and spacing entities.
• Dialog Header (Dialog.tsx):
  • Add gap="size-200" to header Flex for consistent spacing.

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