test(01-02): add failing tests for core pipeline schemas

- Create kb_pipeline package structure
- Add test fixtures in conftest.py
- Add 28 test cases for StepInput, StepOutput, StepStatus, StepRecord, WorkflowState
- Add JSON serialization/deserialization tests
- TDD RED phase: tests fail because schemas.py not yet implemented

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

tests/test_pipeline/conftest.py

@@ -0,0 +1,59 @@
+"""Pytest 配置和共享 fixtures"""
+
+import pytest
+import tempfile
+from pathlib import Path
+from datetime import datetime
+
+
+@pytest.fixture
+def tmp_content_dir():
+    """临时内容目录 fixture"""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        yield Path(tmpdir)
+
+
+@pytest.fixture
+def sample_step_input_data():
+    """示例步骤输入数据"""
+    return {
+        "content_id": "BV1test123",
+        "platform": "bilibili"
+    }
+
+
+@pytest.fixture
+def sample_step_output_data():
+    """示例步骤输出数据"""
+    return {
+        "success": True,
+        "error_message": None,
+        "completed_at": datetime.now()
+    }
+
+
+@pytest.fixture
+def sample_workflow_state_data():
+    """示例工作流状态数据"""
+    return {
+        "schema_version": "1.0",
+        "content_id": "BV1test123",
+        "platform": "bilibili",
+        "source_url": "https://www.bilibili.com/video/BV1test123",
+        "created_at": datetime.now(),
+        "updated_at": datetime.now(),
+        "steps": {}
+    }
+
+
+@pytest.fixture
+def sample_step_record_data():
+    """示例步骤记录数据"""
+    return {
+        "step_name": "fetch_metadata",
+        "status": "completed",
+        "started_at": datetime.now(),
+        "completed_at": datetime.now(),
+        "error_message": None,
+        "output_summary": "成功获取元数据"
+    }