feat: add qa node in workflow builder (#172)

* feat: add qa node in workflow builder

* feat: add qa analysis token usage in usage_info

* fix: mask the API key in QA node

* feat: add advanced configuration in QA node

api/tests/conftest.py

@@ -1,11 +1,18 @@
+"""
+Shared mock fixtures and workflow helpers for unit tests.
+
+Database setup (test DB creation, migrations, session isolation) lives in
+the root api/conftest.py. This module provides lightweight, non-DB fixtures:
+- Mock objects (engine, workflow model, workflow run, user config, tools)
+- Pre-built WorkflowGraph fixtures for various node topologies
+"""
+
 from dataclasses import dataclass, field
 from typing import Any, Dict, Optional
 from unittest.mock import Mock
 
 import pytest
-from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
 
-from api.constants import DATABASE_URL
 from api.services.workflow.dto import (
     EdgeDataDTO,
     ExtractionVariableDTO,
@@ -551,22 +558,3 @@ def three_node_workflow_no_variable_extraction() -> WorkflowGraph:
         ],
     )
     return WorkflowGraph(dto)
-
-
-# =============================================================================
-# Database fixtures for integration tests
-# =============================================================================
-
-
-@pytest.fixture(scope="session")
-async def db_engine():
-    """Create database engine for tests."""
-    engine = create_async_engine(DATABASE_URL, echo=False)
-    yield engine
-    await engine.dispose()
-
-
-@pytest.fixture(scope="session")
-async def db_session_factory(db_engine):
-    """Create session factory for tests."""
-    return async_sessionmaker(bind=db_engine, expire_on_commit=False)