Add Yonyou BIP automation framework with authentication

Features:
- Add auth module (utils/auth.py) for Yonyou BIP login/logout
- Add environment configuration support with python-dotenv
- Add Playwright browser automation with customizable path
- Add comprehensive test suite (tests/) with login/logout tests
- Add dependency management (requirements.txt)
- Add environment variable template (.env.example)

Key capabilities:
- Login with username/password from environment variables
- Auto-handle force login popup
- Logout with confirmation dialog handling
- Configurable headless mode and HTTPS error handling
- Auto-close browser option

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

.env.example

@@ -0,0 +1,7 @@
+# Playwright 浏览器路径
+PLAYWRIGHT_BROWSERS_PATH=C:\Users\Administrator\AppData\Roaming\erpauto\ms-playwright
+
+# 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