wip-feat: mercure alerts

assets/controllers/alert_controller.js

@@ -0,0 +1,18 @@
+import { Controller } from '@hotwired/stimulus';
+
+export default class extends Controller {
+    connect() {
+        let timer = setTimeout(() => {
+                this.element.remove();
+            },
+            "3000"
+        );
+
+        this.element.addEventListener('mouseout', () => timer = setTimeout(() => {
+                this.element.remove();
+            },
+            "3000"
+        ));
+        this.element.addEventListener('mouseover', () => clearTimeout(timer));
+    }
+}