Update favicon and icon set to new RubyUI logo (#463)

Regenerates the full icon set (favicon.ico, 16/32 PNGs, apple-touch, android-chrome 192/512, icon.png) from the new RubyUI symbol, and wires up the previously unused icon.svg as an SVG favicon with a dark-mode adaptive variant.

Author: Sergio-Linkana

docs/app/components/shared/head.rb

@@ -16,6 +16,7 @@ def view_template
           link rel: "apple-touch-icon", sizes: "180x180", href: "/apple-touch-icon.png"
           link rel: "icon", type: "image/png", sizes: "32x32", href: "/favicon-32x32.png"
           link rel: "icon", type: "image/png", sizes: "16x16", href: "/favicon-16x16.png"
+          link rel: "icon", type: "image/svg+xml", href: "/icon.svg"
           link rel: "manifest", href: "/site.webmanifest"
 
           csp_meta_tag