Add Binance SIM market adapter and exchange switch in settings.

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

backend/app/config.py

@@ -33,9 +33,17 @@ class Settings(BaseSettings):
     okx_ws_public: str = "wss://ws.okx.com:8443/ws/v5/public"
     okx_http_proxy: str = ""
 
+    # 币安公共行情（SIM 只读）
+    binance_fapi_base: str = "https://fapi.binance.com"
+    binance_eapi_base: str = "https://eapi.binance.com"
+    binance_futures_ws: str = "wss://fstream.binance.com/stream"
+    binance_options_ws: str = "wss://nbstream.binance.com/eoptions/stream"
+    binance_http_proxy: str = ""
+
     perp_inst_id: str = "ETH-USDT-SWAP"
     option_inst_family: str = "ETH-USD_UM"
     index_inst_id: str = "ETH-USD"
+    option_ct_mult_default: float = 0.01
 
     fee_rate: float = 0.0005
     initial_equity: float = 10_000.0  # SIM 模拟初始资金（USDT），设置页可改
@@ -55,7 +63,6 @@ class Settings(BaseSettings):
     close_bid_mark_max_pct: float = 30.0  # 平仓：买一相对标记最大偏差%
     perp_qty_eth: float = 1.0
     option_qty_eth: float = 2.0
-    option_ct_mult_default: float = 0.01
     db_path: str = ""  # empty -> backend/data/hedge.db
 
     @property
@@ -63,6 +70,23 @@ class Settings(BaseSettings):
         return self.mode.strip().upper() != "LIVE"
 
 
+# 切换交易所时的合约默认
+EXCHANGE_MARKET_DEFAULTS: dict[str, dict[str, str | float]] = {
+    "okx": {
+        "perp_inst_id": "ETH-USDT-SWAP",
+        "option_inst_family": "ETH-USD_UM",
+        "index_inst_id": "ETH-USD",
+        "option_ct_mult_default": 0.01,
+    },
+    "binance": {
+        "perp_inst_id": "ETHUSDT",
+        "option_inst_family": "ETHUSDT",
+        "index_inst_id": "ETHUSDT",
+        "option_ct_mult_default": 1.0,
+    },
+}
+
+
 @lru_cache
 def get_settings() -> Settings:
     return Settings()