perf: remove background-attachment:fixed body gradient (scroll jank + dead code)

background-attachment:fixed disables GPU compositing, causing CPU repaints
on every scroll frame. The image was also fully covered by page-level
Tailwind backgrounds and served no visual purpose.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: JoeMatt

src/app/globals.css

@@ -25,10 +25,3 @@ body {
   font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
 }
 
-/* Site-wide background gradient image (1px-high wide banner repeated vertically) */
-body {
-  background-image: url("../images/banners/blue wide banner graident 1px.png");
-  background-repeat: repeat-y;
-  background-size: 100% auto; /* stretch to full width, keep image height */
-  background-attachment: fixed; /* parallax-like, reduces repaints */
-}