feat(问翻小宝): 增强帮助搜索与会话历史

关键改动：

- 增加问翻小宝会话历史记录规则与测试

- 优化帮助搜索、兜底建议和页面交互结构

- 更新帮助截图资产和截图采集脚本

Co-Authored-By: Codex GPT-5 <codex@openai.com>

apps/web/lib/wenfan-conversation-history.test.ts

@@ -0,0 +1,54 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  createWenfanConversationRecord,
+  deleteWenfanConversationRecord,
+  updateWenfanConversationRecord,
+} from './wenfan-conversation-history';
+
+type TestMessage = {
+  role: 'assistant' | 'user';
+  content?: string;
+};
+
+const introMessage: TestMessage = {
+  role: 'assistant',
+  content: '我是问翻小宝',
+};
+
+test('createWenfanConversationRecord creates history only from the new conversation action', () => {
+  const record = createWenfanConversationRecord('conv-1', [introMessage]);
+
+  assert.equal(record.id, 'conv-1');
+  assert.equal(record.title, '新对话');
+  assert.deepEqual(record.messages, [introMessage]);
+});
+
+test('updateWenfanConversationRecord updates an existing conversation without adding a question record', () => {
+  const record = createWenfanConversationRecord('conv-1', [introMessage]);
+  const messages: TestMessage[] = [
+    introMessage,
+    { role: 'user', content: '怎么新建产品？' },
+    { role: 'assistant', content: '产品创建帮助' },
+    { role: 'user', content: '怎么新建项目？' },
+  ];
+
+  const next = updateWenfanConversationRecord([record], 'conv-1', messages);
+
+  assert.equal(next.length, 1);
+  assert.equal(next[0]?.title, '怎么新建产品？');
+  assert.deepEqual(next[0]?.messages, messages);
+});
+
+test('updateWenfanConversationRecord does not create history when there is no active conversation', () => {
+  const messages: TestMessage[] = [introMessage, { role: 'user', content: '怎么新建产品？' }];
+
+  assert.deepEqual(updateWenfanConversationRecord([], null, messages), []);
+});
+
+test('deleteWenfanConversationRecord removes a conversation history item', () => {
+  const first = createWenfanConversationRecord('conv-1', [introMessage]);
+  const second = createWenfanConversationRecord('conv-2', [introMessage]);
+
+  assert.deepEqual(deleteWenfanConversationRecord([first, second], 'conv-1'), [second]);
+});