Implement browser push notifications

frontend/public/sw.js

@@ -0,0 +1,57 @@
+// Service Worker for Push Notifications
+self.addEventListener("push", function(event) {
+    if (event.data) {
+        const data = event.data.json();
+        
+        const options = {
+            body: data.body,
+            icon: data.icon || "/logo.png",
+            badge: "/logo.png",
+            image: data.image,
+            tag: data.tag || "message",
+            data: data.data,
+            actions: [
+                {
+                    action: "open",
+                    title: "Open Chat"
+                },
+                {
+                    action: "close",
+                    title: "Close"
+                }
+            ],
+            requireInteraction: true,
+            silent: false
+        };
+
+        event.waitUntil(
+            self.registration.showNotification(data.title, options)
+        );
+    }
+});
+
+self.addEventListener("notificationclick", function(event) {
+    event.notification.close();
+
+    if (event.action === "open" || !event.action) {
+        event.waitUntil(
+            clients.matchAll({ type: "window" }).then(function(clientList) {
+                // If there's already a window open, focus it
+                for (let i = 0; i < clientList.length; i++) {
+                    const client = clientList[i];
+                    if (client.url === self.location.origin && "focus" in client) {
+                        return client.focus();
+                    }
+                }
+                // Otherwise, open a new window
+                if (clients.openWindow) {
+                    return clients.openWindow(self.location.origin);
+                }
+            })
+        );
+    }
+});
+
+self.addEventListener("notificationclose", function(event) {
+    // Handle notification close if needed
+});