feat(logger): 添加 winston 日志系统

- 新增 src/lib/logger/ 模块
- 支持 dev/prod 环境不同输出格式
- createLogger() 创建带上下文的 logger
- 更新 AGENTS.md 添加日志使用约定

src/lib/logger/index.ts

@@ -0,0 +1,16 @@
+import { logger } from "./logger";
+
+export { logger };
+
+export function createLogger(context: string) {
+  return {
+    debug: (message: string, meta?: object) =>
+      logger.debug(`[${context}] ${message}`, meta),
+    info: (message: string, meta?: object) =>
+      logger.info(`[${context}] ${message}`, meta),
+    warn: (message: string, meta?: object) =>
+      logger.warn(`[${context}] ${message}`, meta),
+    error: (message: string, meta?: object) =>
+      logger.error(`[${context}] ${message}`, meta),
+  };
+}

src/lib/logger/logger.ts

@@ -0,0 +1,9 @@
+import winston from "winston";
+import { devTransport, prodTransport } from "./transports";
+
+const isDev = process.env.NODE_ENV !== "production";
+
+export const logger = winston.createLogger({
+  level: isDev ? "debug" : "info",
+  transports: [isDev ? devTransport : prodTransport],
+});

src/lib/logger/transports.ts

@@ -0,0 +1,20 @@
+import { transports, format } from "winston";
+
+const { combine, timestamp, printf, colorize, json } = format;
+
+const customFormat = printf(({ level, message, timestamp, ...metadata }) => {
+  const metaStr = Object.keys(metadata).length ? JSON.stringify(metadata) : "";
+  return `${timestamp} [${level}]: ${message} ${metaStr}`;
+});
+
+export const devTransport = new transports.Console({
+  format: combine(
+    colorize(),
+    timestamp({ format: "YYYY-MM-DD HH:mm:ss" }),
+    customFormat
+  ),
+});
+
+export const prodTransport = new transports.Console({
+  format: combine(timestamp(), json()),
+});