Fix illegal constructor error for notifications on mobile

- Changed from new Notification() to registration.showNotification()
- Mobile browsers require ServiceWorkerRegistration API for notifications
- Added vibrate pattern and badge icon for better mobile experience

This fixes the "Illegal constructor" error when enabling push notifications
on Chrome for Android and other mobile browsers.

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

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

index.html

@@ -5406,11 +5406,15 @@
                     updateNotificationUI(true);
                     updateStatus('Push notifications enabled!', 'success');
 
-                    // Test notification
-                    new Notification('HikeMap Notifications Active', {
-                        body: 'You will receive alerts about new geocaches and trail updates',
-                        icon: '/icon-192x192.png'
-                    });
+                    // Test notification using service worker
+                    if ('serviceWorker' in navigator && registration) {
+                        registration.showNotification('HikeMap Notifications Active', {
+                            body: 'You will receive alerts about new geocaches and trail updates',
+                            icon: '/icon-192x192.png',
+                            badge: '/icon-72x72.png',
+                            vibrate: [200, 100, 200]
+                        });
+                    }
                 }
             } catch (error) {
                 console.error('Failed to setup push notifications:', error);