feat(strategies): 实现定制组件（因子、信号生成器、风控）

- strategies/shared/factors/momentum.py: MomentumFactor/TrendFactor/ReversalFactor/VolatilityFactor
- strategies/shared/signals/selectors.py: TopNSelector/TrendFollower/ReversalTrader
- strategies/shared/risk/controls.py: StopLossControl/PositionLimitControl/PremiumControl
- strategies/shared/__init__.py: 统一入口导出所有定制组件

strategies/shared/__init__.py

@@ -0,0 +1,54 @@
+"""
+定制组件统一入口
+
+所有定制因子、信号生成器、风控组件都在这里导出
+"""
+
+# 定制因子
+from strategies.shared.factors.momentum import (
+    MomentumFactor,
+    TrendFactor,
+    ReversalFactor,
+    VolatilityFactor
+)
+
+# 定制信号生成器
+from strategies.shared.signals.selectors import (
+    TopNSelector,
+    TrendFollower,
+    ReversalTrader
+)
+
+# 定制风控组件
+from strategies.shared.risk.controls import (
+    StopLossControl,
+    PositionLimitControl,
+    PremiumControl,
+    premium_filter_callback,
+    crash_filter_callback,
+    holding_time_stoploss_callback
+)
+
+
+__all__ = [
+    # 因子
+    'MomentumFactor',
+    'TrendFactor',
+    'ReversalFactor',
+    'VolatilityFactor',
+    
+    # 信号生成器
+    'TopNSelector',
+    'TrendFollower',
+    'ReversalTrader',
+    
+    # 风控组件
+    'StopLossControl',
+    'PositionLimitControl',
+    'PremiumControl',
+    
+    # 回调函数
+    'premium_filter_callback',
+    'crash_filter_callback',
+    'holding_time_stoploss_callback',
+]