Refactor image rendering in ResultGrid with CSS enhancements

Simplified image rendering logic in `ResultGrid` by removing hover state management within JavaScript. Added `SampleImage.css` to handle hover effects for images and tooltips with scalable zoom. Cleaned up unnecessary comments and improved code readability.

frontend/src/components/ResultGrid.tsx

@@ -2,7 +2,7 @@
 import React, { useEffect, useState } from 'react';
 import { DataGrid, GridColDef } from '@mui/x-data-grid';
 import { OpenAPI, SamplesService } from '../../openapi';
-import './Sampleimage.css';
+import './SampleImage.css';
 
 
 interface ImageInfo {