refactor: clean up imports and unused code in CodeOverview component (#…

…2674)

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## PR-Codex overview
The focus of this PR is to optimize imports, remove unused code, and refactor UI components in the `CodeOverview` component.

### Detailed summary
- Removed unused imports and variables
- Refactored UI structure for better organization
- Updated code snippet rendering logic
- Improved tab functionality for functions and events

> The following files were skipped due to too many changes: `src/contract-ui/tabs/code/components/code-overview.tsx`

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