fix(a11y): add missing alt attributes to img tags to resolve accessibility audit failures

### Bug Description
There are several `` tags across the frontend components that are missing the required `alt` attribute.

Without `alt` text, screen readers cannot interpret the images for visually impaired users, which causes the site to fail WCAG accessibility standards and Google Lighthouse audits.

**Affected Files:**
- `src/pages/features.tsx` (Podman Desktop logo and Selkie mascot)
- `src/components/ui/ArticleCard/index.tsx` (Article cover images)

### Proposed Solution
- Add descriptive `alt` tags to all bare `` elements to properly satisfy accessibility requirements. I have prepared a PR for this!

Start by inspecting the bare img elements in src/pages/features.tsx and src/components/ui/ArticleCard/index.tsx, especially the Podman Desktop logo, Selkie mascot, and article cover images. Add descriptive alt attributes to each affected image, then run the project's accessibility or Lighthouse checks to confirm the audit failures are resolved.

Written by the indexing model from the issue text.