add proper favicon.ico and PNG favicons for all devices

Author: Xavier Araque

favicon-16.png

@@ -5,7 +5,11 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>ShellBar — Ghostty-like terminal with workflow toolbar</title>
   <meta name="description" content="ShellBar is a Ghostty-like terminal emulator with a configurable workflow toolbar. NOT a fork — built on libghostty-vt as an independent library consumer.">
-  <link rel="icon" type="image/png" href="favicon.png">
+  <link rel="icon" type="image/x-icon" href="favicon.ico">
+  <link rel="icon" type="image/png" sizes="16x16" href="favicon-16.png">
+  <link rel="icon" type="image/png" sizes="32x32" href="favicon-32.png">
+  <link rel="icon" type="image/png" sizes="64x64" href="favicon-64.png">
+  <link rel="apple-touch-icon" sizes="128x128" href="logo.png">
   <style>
     * { margin: 0; padding: 0; box-sizing: border-box; }
     body {