docs: add .env.example template

- Provide template for required environment variables
- Document all configuration options
- Help users set up their local environment

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

.env.example

@@ -1,7 +1,11 @@
-# Playwright 浏览器路径
-PLAYWRIGHT_BROWSERS_PATH=C:\Users\Administrator\AppData\Roaming\erpauto\ms-playwright
+# Playwright Configuration
+PLAYWRIGHT_BROWSERS_PATH=path/to/playwright/browsers
 
-# 用友BIP登录配置
-BIP_URL=https://68.11.34.30:8082/yonbip/resources/uap/rbac/login/main/index.html
-BIP_USERNAME=your_username
-BIP_PASSWORD=your_password
+# ERP System Configuration
+ERP_URL=https://your-erp-system.com
+ERP_USERNAME=your_username
+ERP_PASSWORD=your_password
+
+# Browser Behavior
+ERP_HEADLESS=false
+ERP_IGNORE_HTTPS_ERRORS=true