perf(clock): convert background image from PNG to WebP (#683)

Replace bg.png with bg.webp to optimize bundle size. This reduces the compiled bundle from ~10MB to 2.2MB (78% decrease).

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: nicomiguelino

edge-apps/clock/src/css/style.css

@@ -21,7 +21,7 @@ body {
   overflow: hidden;
   color: white;
   font-family: 'Inter', system-ui, sans-serif;
-  background: url('/static/images/bg.png') no-repeat center center;
+  background: url('/static/images/bg.webp') no-repeat center center;
   background-size: cover;
   text-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
 }