Add rounded corners to product images on catalog and details pages

[Copilot]

Overview

This PR implements rounded corners for all product images displayed on the landing page (catalog) and product details page, providing a more modern and polished visual appearance.

Changes

Updated CSS styling in two components to add border-radius: 0.5rem to product images:

1. Catalog Page (Landing Page) - CatalogListItem.razor.css

   • Added rounded corners to product images in the catalog grid view

2. Product Details Page - ItemPage.razor.css

   • Added rounded corners to the main product image on the details page

Visual Impact

• Product images now display with subtle rounded edges instead of sharp corners
• The 0.5rem border-radius provides a modern, professional look
• Consistent styling across both catalog and detail views
• No changes to image dimensions or layout

Technical Details

• Minimal CSS-only changes (2 lines added total)
• No functional changes or breaking modifications
• Build passes successfully with no errors or warnings
• Changes are responsive and work across all viewport sizes

Closes #[issue_number]

Original prompt

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This section details on the original issue you should resolve

<issue_title>Make all product pictures on the landing page round</issue_title>
<issue_description>On the landing page of our webshop we need to make sure that all product pictures are round. I don't mean full circles but rounded edges and they should be round also on the product details page.</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #96

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