Fix Chart.js loading and add favicon support

- Switch from chart.min.js to chart.umd.js for proper module loading
- Add favicon.ico file and proper serving
- Add favicon link in HTML head to prevent 404 errors

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

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

static/index.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>SkyView - ADS-B Aircraft Tracker</title>
+    <link rel="icon" type="image/x-icon" href="/favicon.ico">
     <link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />
     <link rel="stylesheet" href="/static/css/style.css">
 </head>
@@ -96,7 +97,7 @@
     </div>
 
     <script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
-    <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.0/dist/chart.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.0/dist/chart.umd.js"></script>
     <script src="/static/js/app.js"></script>
 </body>
 </html>