Add toast notifications

app/services/toast.js

@@ -0,0 +1,21 @@
+import Service from '@ember/service';
+import { tracked } from '@glimmer/tracking';
+
+export default class ToastService extends Service {
+  @tracked message = null;
+  @tracked isVisible = false;
+  timeoutId = null;
+
+  show(message, duration = 3000) {
+    this.message = message;
+    this.isVisible = true;
+
+    if (this.timeoutId) {
+      clearTimeout(this.timeoutId);
+    }
+
+    this.timeoutId = setTimeout(() => {
+      this.isVisible = false;
+    }, duration);
+  }
+}