Fix image src in preview pages

[lapla-cogito]

This PR resolves an issue with incorrect image paths in news articles on the preview page.

This problem is due to Next.js routing and can be solved by extracting the img element from the string that converted to HTML using jsdom library and rewriting the src attribute correctly.

[github-actions[bot]]

😎 Preview URL: https://lapla-cogito.github.io/Nefront-HP-pr-234-imagepath/

[lapla-cogito]

プレビューページでも画像パスが壊れない