fix: 日志系统修复

- userId 延迟到 finish 事件获取（authMiddleware 已执行）
- 日志记录 UTC 时间戳，支持前端按用户时区显示
- 日期筛选和级别筛选 watch 监听修复
- 添加 showDatePicker 变量定义

server/src/middleware/logger.ts

@@ -23,9 +23,11 @@ function formatTime(date: Date): string {
 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 now = new Date()
+  const time = formatTime(now)
+  const timestamp = now.toISOString() // 记录 UTC 时间戳，前端可按用户时区显示
   const metaStr = meta ? ` ${JSON.stringify(meta)}` : ''
-  const line = `[${time}] ${level} ${message}${metaStr}\n`
+  const line = `[${time}] [${timestamp}] ${level} ${message}${metaStr}\n`
 
   fs.appendFile(logFile, line, (err) => {
     if (err) console.error('[Logger] Write error:', err)
@@ -37,13 +39,12 @@ 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
+  // 响应结束时记录日志（此时 authMiddleware 已执行，userId 可用）
   res.on('finish', () => {
     const duration = Date.now() - startTime
     const { statusCode } = res
+    // 延迟获取 userId，确保 authMiddleware 已执行
+    const userId = (req as any).userId
 
     const meta = {
       method,