fix(machine): point the favicon at logo.png

index.html still linked Vite's scaffold favicon at /vite.svg, which does
not exist in public/ — so every browser tab (the public demo included)
showed a broken icon next to the title. Use the bitSpire logo that is
already shipped for the idle screen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013A6683cCHnQxFUosx1krY4

apps/machine/index.html

@@ -2,7 +2,7 @@
 <html lang="en" class="dark">
   <head>
     <meta charset="UTF-8" />
-    <link rel="icon" type="image/svg+xml" href="/vite.svg" />
+    <link rel="icon" type="image/png" href="/logo.png" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no" />
     <!--
       Content Security Policy: