feat: 多周期牛熊判定模块 — 方案一矩阵展示 + 四法投票 + 多TF策略

- engine/indicators/regime.py: RegimeDetector(四法投票) + MultiTimeframeRegime(多周期并行)
  四法: EMA200斜率 / 价格vsEMA200 / ATH回撤 / 窄幅盘整(<3%振幅)
  全部 O(1)/bar 增量计算,适用于回测和实时
- engine/example/regime_display.py: 多周期牛熊矩阵展示脚本
  独立加载各周期数据 → 运行判定 → 日线对齐矩阵 + 详细拆解 + 统计
  输出 engine/backtest/REGIME_MATRIX_BTCUSDT.md
- engine/example/regime_mtf_strategy.py: 多周期共识策略 + 四策略对比回测
  MTF Consensus: 1w定方向 + 1d确认 + 4h EMA入场
  vs Old Regime(单TF基线) vs Long/Short(无过滤)
- engine/indicators/__init__.py: 导出 RegimeDetector, MultiTimeframeRegime

engine/indicators/__init__.py

@@ -18,6 +18,7 @@ from .momentum import rsi, stoch, stoch_k, stoch_d
 from .volatility import bollinger, bollinger_upper, bollinger_mid, bollinger_lower, atr
 from .volume import obv, vwap
 from .incremental import EmaInc, AtrInc, RsiInc, BbInc
+from .regime import RegimeDetector, MultiTimeframeRegime
 
 __all__ = [
     # 趋势
@@ -30,4 +31,6 @@ __all__ = [
     "obv", "vwap",
     # 增量
     "EmaInc", "AtrInc", "RsiInc", "BbInc",
+    # 牛熊判定
+    "RegimeDetector", "MultiTimeframeRegime",
 ]