币本位买币改为按最大可开张数×权利金×可配缓冲，不全额兑换USDT

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

lib/env/env_schema.py

@@ -104,6 +104,7 @@ HOT_RELOAD_EXACT = frozenset({
     "OKX_OPTIONS_COIN_BUDGET_USDT",
     "OKX_OPTIONS_COIN_MAX_USDT_ENABLED",
     "OKX_OPTIONS_COIN_MAX_USDT",
+    "OKX_OPTIONS_COIN_SPOT_BUY_BUFFER",
     "OKX_TRADE_MODE",
     "MAX_ACTIVE_HEDGE_PLANS",
     "HEDGE_PLAN_LIVE_ORDER",

lib/env/env_ui_manifest.py

@@ -174,6 +174,11 @@ _OPTIONS_SECTION: dict[str, Any] = {
             "币本位单笔上限(USDT)",
             "仅上限开关开启时生效",
         ),
+        (
+            "OKX_OPTIONS_COIN_SPOT_BUY_BUFFER",
+            "币本位现货买入缓冲",
+            "相对权利金倍数,默认 1.10(=多买10%);也可写 0.10 表示+10%。按最大可开张数×卖一权利金×本缓冲买币,不全额兑换",
+        ),
         (
             "OKX_OPTIONS_COMPOUND_FULL_ENABLED",
             "全仓复利开关",