Fix crosselling thumbnail cropping in Everblock carousel

[CySSoO]

Motivation

• Cross-selling thumbnails inside Everblock blocks were being cropped on some viewports, causing poor product image display.
• The intent is to ensure the cross-selling shortcode output receives the same class-based styling on mobile and that thumbnails keep their aspect ratio.

Description

• Add the shortcode class to the mobile featured-products section by updating views/templates/hook/ever_presented_products.tpl so the shortcodeClass (e.g. crosselling) is present on the mobile carousel container.
• Add cross-selling specific CSS in views/css/everblock.css (selector .ever-featured-products.crosselling .thumbnail-container and .product-thumbnail img) to center thumbnails and use object-fit: contain to avoid cropping.

Testing

• No automated tests were run; changes are limited to a template and stylesheet and should be verifiable visually in a storefront preview.

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Codex Task