fix: use explicit crypto import for Node 18 compatibility

crypto.randomUUID() is not globally available in Node 18. Import
randomUUID from node:crypto explicitly so the framework works on
all supported Node versions (>=18).

src/task/task.ts

@@ -6,6 +6,7 @@
  * Stateful orchestration belongs in {@link TaskQueue}.
  */
 
+import { randomUUID } from 'node:crypto'
 import type { Task, TaskStatus } from '../types.js'
 
 // ---------------------------------------------------------------------------
@@ -33,7 +34,7 @@ export function createTask(input: {
 }): Task {
   const now = new Date()
   return {
-    id: crypto.randomUUID(),
+    id: randomUUID(),
     title: input.title,
     description: input.description,
     status: 'pending' as TaskStatus,

src/team/messaging.ts

@@ -6,6 +6,8 @@
  * for replay and audit; read-state is tracked per recipient.
  */
 
+import { randomUUID } from 'node:crypto'
+
 // ---------------------------------------------------------------------------
 // Message type
 // ---------------------------------------------------------------------------
@@ -93,7 +95,7 @@ export class MessageBus {
    */
   send(from: string, to: string, content: string): Message {
     const message: Message = {
-      id: crypto.randomUUID(),
+      id: randomUUID(),
       from,
       to,
       content,