refactor(experiment): 重构模型保存机制，支持 processors 持久化

- 模型保存路径改为 models/{model_type}/ 目录结构
- save_model_with_factors 新增 fitted_processors 参数
- 新增 load_processors 函数加载处理器状态
- Storage 查询排序优化：ORDER BY ts_code, trade_date

src/data/storage.py

@@ -217,7 +217,7 @@ class Storage:
             params.append(ts_code)
 
         where_clause = f"WHERE {' AND '.join(conditions)}" if conditions else ""
-        query = f"SELECT * FROM {name} {where_clause} ORDER BY trade_date"
+        query = f"SELECT * FROM {name} {where_clause} ORDER BY ts_code, trade_date"
 
         try:
             # Execute query with parameters (SQL injection safe)
@@ -255,7 +255,7 @@ class Storage:
             conditions.append(f"ts_code = '{ts_code}'")
 
         where_clause = f"WHERE {' AND '.join(conditions)}" if conditions else ""
-        query = f"SELECT * FROM {name} {where_clause} ORDER BY trade_date"
+        query = f"SELECT * FROM {name} {where_clause} ORDER BY ts_code, trade_date"
 
         # 使用 DuckDB 的 Polars 导出（需要 pyarrow）
         df = self._connection.sql(query).pl()