docs: 交付文档、维护指引与端到端回归

补齐 README、开发计划、维护交接与 E2E 用例，执行最终验收。

e2e/specs/widget/widget-chat.spec.ts

@@ -0,0 +1,41 @@
+import { test, expect, AI_REPLY } from '@e2e'
+
+test.describe('widget chat', () => {
+  test('a customer gets the agent\'s answer @smoke @widget', async ({ agent, widget, llm }) => {
+    await llm.script(agent, (s) => s
+      .when(/opening hours/i).reply('We are open 9am to 5pm, Monday to Friday.')
+      .otherwise().reply('Happy to help!'))
+
+    await widget.embed()
+    await widget.open()
+    await widget.send('What are your opening hours?')
+
+    await expect(widget.lastAgentMessage()).toHaveText('We are open 9am to 5pm, Monday to Friday.', AI_REPLY)
+  })
+
+  test('the conversation is still there after the customer reloads the page @widget', async ({ agent, widget, llm }) => {
+    await llm.script(agent, (s) => s.otherwise().reply('Your order ships tomorrow.'))
+
+    await widget.embed()
+    await widget.open()
+    await widget.send('Where is my order?')
+    await expect(widget.lastAgentMessage()).toHaveText('Your order ships tomorrow.', AI_REPLY)
+
+    await widget.page.reload()
+    await widget.open()
+    await expect(widget.customerMessages.last()).toHaveText('Where is my order?')
+    await expect(widget.lastAgentMessage()).toHaveText('Your order ships tomorrow.', AI_REPLY)
+  })
+
+  test('a visitor whose first authorization went missing can still chat @widget', async ({ agent, widget, llm }) => {
+    await llm.script(agent, (s) => s.otherwise().reply('Happy to help!'))
+
+    // The socket refuses the anonymous token; the widget authorizes again and connects.
+    await widget.loseFirstAuthorization()
+    await widget.embed()
+    await widget.open()
+    await widget.send('Hello?')
+
+    await expect(widget.lastAgentMessage()).toHaveText('Happy to help!', AI_REPLY)
+  })
+})