feat: complete customer service safety and handover flow

tests/unit/core/test_conversation_privacy.py

@@ -0,0 +1,26 @@
+from app.core.conversation_privacy import sanitize_customer_service_message
+
+
+def test_customer_service_message_hides_sensitive_credentials_before_storage() -> None:
+    """敏感值不得进入客服会话持久化和后续异步处理链。"""
+    message = (
+        "登录密码: Secret123；验证码 123456；身份证 11010519491231002X；"
+        "银行卡 6222021234567890123；手机号 13812345678"
+    )
+
+    sanitized = sanitize_customer_service_message(message)
+
+    assert "Secret123" not in sanitized
+    assert "123456" not in sanitized
+    assert "11010519491231002X" not in sanitized
+    assert "6222021234567890123" not in sanitized
+    assert "13812345678" not in sanitized
+    assert "登录密码" in sanitized
+    assert "验证码" in sanitized
+
+
+def test_customer_service_message_keeps_ordinary_password_question_unchanged() -> None:
+    """普通业务咨询不应被误判为用户实际提交的密码。"""
+    message = "忘记登录密码怎么办？"
+
+    assert sanitize_customer_service_message(message) == message