feat(ui): add mobile responsiveness and favicon

- Add comprehensive responsive styles for tablets (1024px), phones (768px, 480px)
- Add touch optimization media query for larger tap targets
- Add SVG favicon with lightning bolt icon
- Add meta description and theme-color tags
- Add dynamic page title updates based on session/timer state
- Update README with keyboard shortcuts documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/index.html

@@ -3,7 +3,10 @@
 <head>
   <meta charset="UTF-8">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <meta name="description" content="Claude Code session manager with web interface">
+  <meta name="theme-color" content="#0a0a0a">
   <title>Claudeman</title>
+  <link rel="icon" type="image/svg+xml" href="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 32 32'%3E%3Cdefs%3E%3ClinearGradient id='g' x1='0%25' y1='0%25' x2='100%25' y2='100%25'%3E%3Cstop offset='0%25' stop-color='%2360a5fa'/%3E%3Cstop offset='100%25' stop-color='%233b82f6'/%3E%3C/linearGradient%3E%3C/defs%3E%3Crect width='32' height='32' rx='6' fill='%230a0a0a'/%3E%3Cpath d='M18 4L8 18h6l-2 10 10-14h-6z' fill='url(%23g)'/%3E%3C/svg%3E">
   <link rel="stylesheet" href="styles.css">
   <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/xterm@5.3.0/css/xterm.css">
   <script src="https://cdn.jsdelivr.net/npm/xterm@5.3.0/lib/xterm.min.js"></script>