Use system fonts for offline support

Remove Google Fonts dependency to ensure the web UI works
completely offline. Uses high-quality system font stacks:
- Mono: ui-monospace, SF Mono, Menlo, Consolas
- Sans: system-ui, Segoe UI, Roboto, Helvetica Neue

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/static/style.css

@@ -45,9 +45,9 @@
   --space-xl: 2rem;
   --space-2xl: 3rem;
 
-  /* Typography */
-  --font-mono: 'IBM Plex Mono', 'JetBrains Mono', 'Fira Code', monospace;
-  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
+  /* Typography - system fonts only for offline support */
+  --font-mono: ui-monospace, 'SF Mono', SFMono-Regular, Menlo, Consolas, 'Liberation Mono', monospace;
+  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
 
   /* Transitions */
   --transition-fast: 150ms ease;

app/templates/base.html

@@ -5,11 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>{% block title %}Algo VPN{% endblock %}</title>
 
-    <!-- Fonts: JetBrains Mono for headers, IBM Plex Sans for body -->
-    <link rel="preconnect" href="https://fonts.googleapis.com">
-    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
-    <link href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;600&family=IBM+Plex+Sans:wght@400;500;600&display=swap" rel="stylesheet">
-
+    <!-- All assets served locally for offline support -->
     <link rel="stylesheet" href="/static/style.css">
     <script src="/static/htmx.min.js" defer></script>
     <script src="/static/htmx-sse.js" defer></script>