chore: 添加 CLAUDE.md 和 .env 配置文件

- 添加项目文档 CLAUDE.md，包含常用命令和架构说明
- 添加 packages/server/.env 环境变量配置文件

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/server/.env

@@ -0,0 +1,21 @@
+# Database
+DATABASE_URL=mysql://root:AK8jyLfsfMA5wNdC@129.204.155.94:13306/db_mp_focus
+
+# JWT
+JWT_SECRET=change-me-to-a-secure-random-string
+
+# WeChat Mini Program
+WX_APPID=wx3e7a133d2305fa2c
+WX_SECRET=92f4f91af72ca0705d65e39e605cb98b
+
+# WeChat Pay
+WX_MCH_ID=1110530023
+WX_MCH_KEY=ACbGcH3FNLBacmvmIVR4uWXjNf9h8jQ2
+WX_MCH_SERIAL_NO=7A90D96A7ED1A129E98DB5FD5F3A84EDC34B2AC6
+WX_MCH_KEY_PATH=./certs/apiclient_key.pem
+
+# API Base URL (used for WeChat Pay callback notification)
+API_BASE_URL=https://focus.richarjiang.com/
+
+# Server
+PORT=3000