feat: render flash messages as toasts

Co-Authored-By: Claude Opus 5 <[email protected]>

assets/controllers/toast_controller.js

@@ -0,0 +1,22 @@
+import { Controller } from '@hotwired/stimulus';
+import Toastify from 'toastify-js';
+
+/**
+ * Turns one flash message into one toast. The element itself stays empty and invisible --
+ * Toastify appends its own node to the body, which is why a toast outlives the out-of-band
+ * swap of #flashes that spawned it.
+ */
+export default class extends Controller {
+    static values = { text: String, class: String };
+
+    connect() {
+        Toastify({
+            text: this.textValue,
+            className: this.classValue,
+            duration: 5000,
+            gravity: 'top',
+            position: 'right',
+            close: true,
+        }).showToast();
+    }
+}