Add web push notifications

sw.js

@@ -0,0 +1,25 @@
+self.addEventListener('push', event => {
+  let data = {};
+  try { data = event.data ? event.data.json() : {}; } catch (e) { data = { title: 'MVLog', body: event.data ? event.data.text() : 'New video published' }; }
+  const title = data.title || 'MVLog';
+  const options = {
+    body: data.body || 'New video published',
+    icon: 'assets/img/moto_travel.png',
+    badge: 'assets/img/moto_travel.png',
+    data: { url: data.url || './' },
+    tag: data.tag || 'mvlog-new-video',
+    renotify: true
+  };
+  event.waitUntil(self.registration.showNotification(title, options));
+});
+
+self.addEventListener('notificationclick', event => {
+  event.notification.close();
+  const url = event.notification.data && event.notification.data.url ? event.notification.data.url : './';
+  event.waitUntil(clients.matchAll({ type: 'window', includeUncontrolled: true }).then(clientList => {
+    for (const client of clientList) {
+      if (client.url === url && 'focus' in client) return client.focus();
+    }
+    return clients.openWindow(url);
+  }));
+});