feat: 请求日志 + 前端埋点系统

后端：
- 新增 logger 中间件，记录所有请求到 logs/ 目录
- 新增 /api/track 接口接收前端埋点数据

前端：
- 新增 tracker 工具，支持页面访问/操作/错误埋点
- request.ts 添加 API 错误自动埋点
- App.vue 初始化全局错误追踪

文档：
- CLAUDE.md 更新项目结构
- DEV.md 添加埋点和日志说明

server/src/middleware/logger.ts

@@ -0,0 +1,84 @@
+import { Request, Response, NextFunction } from 'express'
+import fs from 'fs'
+import path from 'path'
+
+// 日志目录
+const LOG_DIR = path.resolve(process.env.LOG_DIR || './logs')
+if (!fs.existsSync(LOG_DIR)) {
+  fs.mkdirSync(LOG_DIR, { recursive: true })
+}
+
+/** 获取当前日期字符串 YYYY-MM-DD */
+function getDateStr(): string {
+  const d = new Date()
+  return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`
+}
+
+/** 格式化时间 HH:mm:ss.SSS */
+function formatTime(date: Date): string {
+  return `${String(date.getHours()).padStart(2, '0')}:${String(date.getMinutes()).padStart(2, '0')}:${String(date.getSeconds()).padStart(2, '0')}.${String(date.getMilliseconds()).padStart(3, '0')}`
+}
+
+/** 写入日志文件 */
+function writeLog(level: string, message: string, meta?: Record<string, any>) {
+  const dateStr = getDateStr()
+  const logFile = path.join(LOG_DIR, `${dateStr}.log`)
+  const time = formatTime(new Date())
+  const metaStr = meta ? ` ${JSON.stringify(meta)}` : ''
+  const line = `[${time}] ${level} ${message}${metaStr}\n`
+
+  fs.appendFile(logFile, line, (err) => {
+    if (err) console.error('[Logger] Write error:', err)
+  })
+}
+
+/** 请求日志中间件 */
+export function requestLogger(req: Request, res: Response, next: NextFunction) {
+  const startTime = Date.now()
+  const { method, url, ip } = req
+
+  // 提取用户 ID（如果有 auth 中间件设置）
+  const userId = (req as any).userId
+
+  // 响应结束时记录日志
+  res.on('finish', () => {
+    const duration = Date.now() - startTime
+    const { statusCode } = res
+
+    const meta = {
+      method,
+      url,
+      status: statusCode,
+      duration: `${duration}ms`,
+      ip: ip || req.headers['x-forwarded-for'] || 'unknown',
+      userId: userId || null,
+      userAgent: req.headers['user-agent']?.slice(0, 100) || ''
+    }
+
+    if (statusCode >= 400) {
+      writeLog('ERROR', `${method} ${url} ${statusCode} ${duration}ms`, meta)
+    } else if (duration > 1000) {
+      writeLog('WARN', `Slow request: ${method} ${url} ${duration}ms`, meta)
+    } else {
+      writeLog('INFO', `${method} ${url} ${statusCode} ${duration}ms`, meta)
+    }
+  })
+
+  next()
+}
+
+/** 错误日志 */
+export function logError(message: string, error: Error | any, meta?: Record<string, any>) {
+  writeLog('ERROR', message, {
+    ...meta,
+    error: error?.message || String(error),
+    stack: error?.stack?.slice(0, 500) || ''
+  })
+}
+
+/** 业务日志 */
+export function logInfo(message: string, meta?: Record<string, any>) {
+  writeLog('INFO', message, meta)
+}
+
+export default { requestLogger, logError, logInfo }