Deduplicate guest tasks list and restore header icon

resources/js/guest/lib/taskUtils.ts

@@ -0,0 +1,18 @@
+export type TaskIdentity = {
+  id: number;
+};
+
+export function dedupeTasksById<T extends TaskIdentity>(tasks: T[]): T[] {
+  const seen = new Set<number>();
+  const unique: T[] = [];
+
+  tasks.forEach((task) => {
+    if (seen.has(task.id)) {
+      return;
+    }
+    seen.add(task.id);
+    unique.push(task);
+  });
+
+  return unique;
+}