chore(site): diagram mobile and favicon (#49)

docs/favicon.svg

@@ -1,10 +1 @@
-<svg width="32" height="32" viewBox="0 0 32 32" fill="none" xmlns="http://www.w3.org/2000/svg">
-  <rect width="32" height="32" rx="6" fill="url(#bg_gradient)"/>
-  <text x="16" y="22" text-anchor="middle" font-family="system-ui, -apple-system, sans-serif" font-size="16" font-weight="700" fill="white">SA</text>
-  <defs>
-    <linearGradient id="bg_gradient" x1="0" y1="0" x2="32" y2="32" gradientUnits="userSpaceOnUse">
-      <stop stop-color="#16A34A"/>
-      <stop offset="1" stop-color="#15803D"/>
-    </linearGradient>
-  </defs>
-</svg>
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