refactor: v2 重构 — 模块化拆分 + AI Prompt模板化 + 前端状态管理

P0 - AI交互层:
- ai/prompt.js: 模块化 Prompt 模板
- ai/validator.js: JSON Schema 校验 + normalize
- ai/client.js: DeepSeek API 封装
- 金额计算唯一化，时间格式归一化

P1 - 后端架构:
- routes/: auth/rooms/messages/purchases 独立路由
- middleware/auth.js: 认证授权中间件
- ws/index.js: WebSocket 连接管理
- db.js: 启用 foreign_keys
- server.js: 从588行精简到40行入口

P2 - 前端架构:
- public/css/style.css: CSS 独立
- public/js/store.js: 全局状态 Store
- public/js/{chat,ws,purchases,auth}.js: 功能模块拆分
- index.html: 纯 HTML 结构, v2.6

server/routes/rooms.js

@@ -0,0 +1,57 @@
+// 群聊管理路由
+const express = require('express');
+const { v4: uuidv4 } = require('uuid');
+const { authMiddleware, adminOnly } = require('../middleware/auth');
+const { broadcast } = require('../ws');
+const db = require('../db');
+const { timestamp } = require('../utils');
+
+const router = express.Router();
+
+router.get('/', authMiddleware, (req, res) => {
+  const username = req.user.username;
+  const isAdmin = req.user.isAdmin;
+  let rooms;
+  if (isAdmin) {
+    rooms = db.prepare('SELECT * FROM rooms').all();
+  } else {
+    rooms = db.prepare("SELECT * FROM rooms WHERE white_list = '' OR (',' || white_list || ',' LIKE ?)").all(`%,${username},%`);
+  }
+  const result = rooms.map(room => {
+    const lastMsg = db.prepare('SELECT text, timestamp FROM messages WHERE room_id = ? ORDER BY id DESC LIMIT 1').get(room.id);
+    return { ...room, last_message: lastMsg ? lastMsg.text : '', last_time: lastMsg ? lastMsg.timestamp : '' };
+  });
+  res.json(result);
+});
+
+router.post('/', authMiddleware, adminOnly, (req, res) => {
+  const { name, whiteList } = req.body;
+  const id = uuidv4();
+  const now = timestamp();
+  db.prepare('INSERT INTO rooms (id, name, created_by, white_list, created_at) VALUES (?,?,?,?,?)').run(id, name, req.user.username, whiteList || '', now);
+  broadcast({ type: 'room_created', room: { id, name, white_list: whiteList || '' } });
+  res.json({ id, name });
+});
+
+router.put('/:roomId', authMiddleware, adminOnly, (req, res) => {
+  const { name, whiteList } = req.body;
+  const roomId = req.params.roomId;
+  const room = db.prepare('SELECT * FROM rooms WHERE id = ?').get(roomId);
+  if (!room) return res.status(404).json({ error: '群聊不存在' });
+  db.prepare('UPDATE rooms SET name = ?, white_list = ? WHERE id = ?').run(name, whiteList || '', roomId);
+  broadcast({ type: 'room_updated', room: { id: roomId, name, white_list: whiteList || '' } });
+  res.json({ success: true });
+});
+
+router.delete('/:roomId', authMiddleware, adminOnly, (req, res) => {
+  const roomId = req.params.roomId;
+  db.prepare('DELETE FROM messages WHERE room_id = ?').run(roomId);
+  db.prepare('DELETE FROM purchase_attachments WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
+  db.prepare('DELETE FROM purchase_history WHERE purchase_id IN (SELECT id FROM purchases WHERE room_id = ?)').run(roomId);
+  db.prepare('DELETE FROM purchases WHERE room_id = ?').run(roomId);
+  db.prepare('DELETE FROM rooms WHERE id = ?').run(roomId);
+  broadcast({ type: 'room_deleted', roomId });
+  res.json({ success: true });
+});
+
+module.exports = router;