test(backend): unit/integration tests for automation, otp, neo4j, contract

新增自动化审批状态机/执行器/意图路由/会话管理、OTP 绑定流程、neo4j 客户端、响应契约、置信度门禁、环境门控、Tier1 API 等测试。

backend/tests/conftest.py

@@ -20,8 +20,8 @@ import starlette.config as _starlette_config
 import io as _io
 
 
-def _patched_read_file(self, env_file):
-    """强制 utf-8 编码读 .env,绕开 Windows GBK 默认值。"""
+def _patched_read_file(self, env_file, encoding=None):
+    """强制 utf-8 编码读 .env,绕开 Windows GBK 默认值。新版 starlette 传 encoding 参数，兼容接受。"""
     if not env_file:
         return {}
     try: