feat(factor): data_adapter BarData→AlphaLab polars 转换

实现 Task 4: 数据转换层

✅ 实现功能:
- convert_bars_to_alpha_df: BarData → polars DataFrame
- save_alpha_lab_data: 保存到 AlphaLab 格式

🔧 SPIKE 修正:
- 列名使用 open/high/low/close (非 open_price/close_price)
- 对齐 AlphaLab.save_bar_data 的 parquet 格式

📝 文件:
- sanguo_factor/data_adapter.py (核心实现)
- sanguo_factor/__init__.py (模块初始化)
- tests/factor/test_data_adapter.py (TDD 测试)
- tests/factor/conftest.py (测试配置)
- tests/factor/__init__.py (测试包)

⚠️  Environment Note:
- polars 依赖在 Python 3.14 环境安装困难
- 代码逻辑正确，待环境配置后验证测试

sanguo_factor/__init__.py

@@ -0,0 +1 @@
+"""Sanguo factor module for vnpy alpha strategies."""

sanguo_factor/data_adapter.py

@@ -0,0 +1,69 @@
+"""Phase 1 BarData → vnpy.alpha AlphaLab polars 格式转换。"""
+import sys
+import os
+_VNPY_SRC = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "vnpy_v4.4.0"))
+if _VNPY_SRC not in sys.path:
+    sys.path.insert(0, _VNPY_SRC)
+
+import polars as pl
+from pathlib import Path
+from vnpy.trader.object import BarData
+
+
+def convert_bars_to_alpha_df(bars: list[BarData]) -> pl.DataFrame:
+    """
+    Convert vnpy BarData list to AlphaLab polars DataFrame format.
+
+    Args:
+        bars: List of BarData objects from Phase 1 read_db_daily
+
+    Returns:
+        polars DataFrame with columns: vt_symbol, datetime, open, high, low, close, volume, turnover, open_interest
+
+    Note:
+        SPIKE CORRECTION: AlphaLab.save_bar_data stores parquet columns as
+        datetime, vt_symbol, open, high, low, close, volume, turnover, open_interest
+        (NOT open_price, close_price - this was corrected in S1 spike testing)
+    """
+    if not bars:
+        return pl.DataFrame(schema={
+            "vt_symbol": pl.Utf8,
+            "datetime": pl.Datetime,
+            "open": pl.Float64,
+            "high": pl.Float64,
+            "low": pl.Float64,
+            "close": pl.Float64,
+            "volume": pl.Float64,
+            "turnover": pl.Float64,
+            "open_interest": pl.Float64,
+        })
+
+    return pl.DataFrame({
+        "vt_symbol": [b.vt_symbol for b in bars],
+        "datetime": [b.datetime for b in bars],
+        "open": [b.open_price for b in bars],
+        "high": [b.high_price for b in bars],
+        "low": [b.low_price for b in bars],
+        "close": [b.close_price for b in bars],
+        "volume": [float(b.volume) for b in bars],
+        "turnover": [float(b.turnover) if b.turnover is not None else 0.0 for b in bars],
+        "open_interest": [float(b.open_interest) if b.open_interest is not None else 0.0 for b in bars],
+    })
+
+
+def save_alpha_lab_data(bars: list[BarData], lab_path: str) -> Path:
+    """
+    Save BarData to AlphaLab format for vnpy.alpha usage.
+
+    Args:
+        bars: List of BarData objects
+        lab_path: Path to AlphaLab directory
+
+    Returns:
+        Path to the saved daily data file
+    """
+    from vnpy.alpha.lab import AlphaLab
+
+    lab = AlphaLab(lab_path)
+    lab.save_bar_data(bars)
+    return lab.daily_path