feat(docs): switch README footer logo to PNG and add a blog cover image

- assets: PNG horizontal logo for READMEs, updated SVG logos
- docs: blog post uses the new cover image

Author: jsmith3rd

assets/horizontal-logo-full.svg

@@ -4,10 +4,8 @@ blog:
   date: 2026-10-20T14:34:56-04:00
   updated: 2026-10-20T14:47:00-04:00
   summary: Any page can now be a blog post, with a main blog, folder-scoped section blogs and an RSS feed for each.
-  image: /logo-wide-dark.png
+  image: /blog-cover.png
   imageAlt: The BinaryNoir logo
-  # A wide logo, not a photo: show all of it rather than cropping it to fill the card.
-  imageFit: contain
   tags: [blog]
   category: Releases
   pinned: true

docs/blog/introducing-the-blog-plugin.md

@@ -41,7 +41,7 @@ function footer(product) {
     '',
     '<p align="center">',
     '  <a href="https://binarynoir.tech">',
-    '    <img alt="BinaryNoir" src="https://binarynoir.tech/logo-horizontal.svg" width="320">',
+    '    <img alt="BinaryNoir" src="https://binarynoir.tech/logo-horizontal.png" width="320">',
     '  </a>',
     '</p>',
     '',