fix(factor-engine): 修复多因子计算时数据规格字段合并的 bug

- 修复 FactorEngine.compute() 中相同表的字段未正确合并的问题
- 将简单去重改为字段集合合并，确保所有因子依赖的字段都被获取
- 解决 high_low_ratio 等需要 high/low 字段的因子计算失败问题

src/experiment/learn_to_rank.py

@@ -302,14 +302,14 @@ SELECTED_FACTORS = [
     "return_5_rank",
     "EP_rank",
     "pe_expansion_trend",
-    # "value_price_divergence",
+    "value_price_divergence",
     "active_market_cap",
-    # "ebit_rank",
+    "ebit_rank",
 ]
 
 # 因子定义字典（完整因子库）
 FACTOR_DEFINITIONS = {
-    # "turnover_rate_volatility": "ts_std(log(turnover_rate), 20)"
+    "turnover_rate_volatility": "ts_std(log(turnover_rate), 20)"
 }
 
 # Label 因子定义（不参与训练，用于计算目标）