Add risk leverage basis option: actual ask vs selection leverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/config.py

@@ -74,6 +74,8 @@ class Settings(BaseSettings):
     perp_margin_mode: str = "cross"
     min_option_hours: float = 12.0  # 期权最小剩余小时
     min_option_leverage: float = 100.0  # 现价/卖一权利金 下限
+    # 以损定仓权利金口径：actual=盘口卖一；selection=指数/选约杠杆（控节奏，默认）
+    risk_leverage_basis: str = "selection"
     atm_open_offset_enabled: bool = False  # 开仓 ATM 偏差限制开关（默认关）
     max_atm_open_offset: float = 3.0  # 开启后：|ATM行权价−标的| 上限（点）
     # 固定方向：关=现有 ATM/比价规则；开=指定永续多/空，期权 Put/Call 且须实值或平值