Update image lazy loading behavior in post-card.hbs

[0xsuid]

Description

• Disabled lazy loading for the first image to improve perceived page load speed and Largest Contentful Paint (LCP) metrics.
• Updated the loading attribute to be dynamic:

  loading="{{#if @index}}lazy{{else}}eager{{/if}}"

• The first image (@index = 0) now uses eager loading.
• All subsequent images continue to use lazy loading.

Why:

Improving the loading strategy for critical content enhances user experience and boosts SEO performance by optimizing core web vitals