Added stimulus and turbo. Added first controller to close sidebar.

assets/app.js

@@ -1,3 +1,4 @@
+import './bootstrap.js';
 /*
  * Welcome to your app's main JavaScript file!
  *

assets/bootstrap.js

@@ -0,0 +1,5 @@
+import { startStimulusApp } from '@symfony/stimulus-bundle';
+
+const app = startStimulusApp();
+// register any custom, 3rd party controllers here
+// app.register('some_controller_name', SomeImportedController);

assets/controllers.json

@@ -0,0 +1,15 @@
+{
+    "controllers": {
+        "@symfony/ux-turbo": {
+            "turbo-core": {
+                "enabled": true,
+                "fetch": "eager"
+            },
+            "mercure-turbo-stream": {
+                "enabled": false,
+                "fetch": "eager"
+            }
+        }
+    },
+    "entrypoints": []
+}

assets/controllers/closable_controller.js

@@ -0,0 +1,15 @@
+import { Controller } from '@hotwired/stimulus';
+
+export default class extends Controller {
+    async close(){
+        this.element.style.width = '0';
+        await this.#waitForAnimation();
+        this.element.remove();
+    }
+
+    #waitForAnimation() {
+        return Promise.all(
+            this.element.getAnimations().map((animation) => animation.finished),
+        );
+    }
+}

assets/controllers/hello_controller.js

@@ -0,0 +1,16 @@
+import { Controller } from '@hotwired/stimulus';
+
+/*
+ * This is an example Stimulus controller!
+ *
+ * Any element with a data-controller="hello" attribute will cause
+ * this controller to be executed. The name "hello" comes from the filename:
+ * hello_controller.js -> "hello"
+ *
+ * Delete this file or adapt it for your use!
+ */
+export default class extends Controller {
+    connect() {
+        this.element.textContent = 'Hello Stimulus! Edit me in assets/controllers/hello_controller.js';
+    }
+}