Add dual exit modes: fixed USDT or premium multiple.

Net PnL (after estimated close fees) drives auto close; Plan/Settings expose the choice.

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

backend/app/config.py

@@ -42,8 +42,11 @@ class Settings(BaseSettings):
     max_rounds: int = 3  # 已不再强管控，仅兼容旧字段
     open_hhmm: str = "16:00"  # 已废弃开仓窗
     stop_open_hhmm: str = "08:00"  # 已废弃开仓窗
-    exit_move_points: float = 30.0  # 旧字段，改用 exit_move_pct
-    exit_move_pct: float = 2.0  # 相对开仓指数波动 % 全平
+    exit_move_points: float = 30.0  # 旧字段，已废弃
+    exit_move_pct: float = 2.0  # 旧字段，已废弃（改用净盈利出场）
+    exit_mode: str = "fixed_usdt"  # fixed_usdt | premium_multiple
+    net_profit_target: float = 15.0  # fixed_usdt：净盈利 ≥ 该值（USDT）
+    premium_exit_multiple: float = 1.0  # premium_multiple：净盈利 ≥ 权利金×倍数
     rest_seconds: int = 300
     leverage: float = 3.0  # 永续杠杆
     min_option_hours: float = 12.0  # 期权最小剩余小时