feat: add ClockApp and SettingsPanel components with customizable settings

- Implemented ClockApp component to display time based on user settings.
- Created SettingsPanel for users to adjust clock type, time format, timezone, and theme.
- Added hooks for managing time, settings persistence, and fullscreen functionality.
- Introduced types for clock settings and themes, including default settings.
- Integrated URL parameter parsing for sharing clock configurations.
- Enhanced user experience with loading states and visual transitions.

src/app/robots.ts

@@ -0,0 +1,22 @@
+import { MetadataRoute } from 'next';
+
+export default function robots(): MetadataRoute.Robots {
+  return {
+    rules: [
+      {
+        userAgent: '*',
+        allow: '/',
+        disallow: ['/api/', '/_next/'],
+      },
+      {
+        userAgent: 'Googlebot',
+        allow: '/',
+      },
+      {
+        userAgent: 'Bingbot',
+        allow: '/',
+      },
+    ],
+    sitemap: 'https://clock.arthurp.fr/sitemap.xml',
+  };
+}