🤖 feat: add favicon to mux server (#789)

Serve the app icon (icon-192.png) as `/favicon.ico` so browsers display
the mux icon in tabs when using mux-server.

_Generated with `mux`_

Author: ibetitsmike

index.html

@@ -9,7 +9,8 @@
     <meta name="description" content="Parallel agentic development with Electron + React" />
     <meta name="theme-color" content="#1e1e1e" />
     <link rel="manifest" href="/manifest.json" />
-    <link rel="apple-touch-icon" href="/icon-192.png" />
+    <link rel="icon" href="/favicon.ico" />
+    <link rel="apple-touch-icon" href="/icon.png" />
     <title>mux - coder multiplexer</title>
     <style>
       body {

public/favicon.ico

@@ -9,13 +9,7 @@
   "orientation": "any",
   "icons": [
     {
-      "src": "/icon-192.png",
-      "sizes": "192x192",
-      "type": "image/png",
-      "purpose": "any maskable"
-    },
-    {
-      "src": "/icon-512.png",
+      "src": "/icon.png",
       "sizes": "512x512",
       "type": "image/png",
       "purpose": "any maskable"