Remove USDC product path; CoinOX is coin-margined only.

Drop USDC open/quote/swap APIs and env knobs; retarget hedge/settings copy to USDT/coin.

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

lib/instance/instance_display_prefs_lib.py

@@ -26,7 +26,7 @@ DEFAULT_INSTANCE_DISPLAY: dict[str, bool] = {
     "show_settings_transfer": True,
     "show_settings_export": True,
     "show_settings_password": True,
-    "show_settings_options_swap": True,
+    "show_settings_options_swap": False,  # CoinOX 已移除 USDT↔USDC 兑换
     "show_settings_options_transfer": True,
 }
 
@@ -86,6 +86,7 @@ def normalize_display_prefs(raw: dict | None) -> dict[str, bool]:
     out["show_nav_strategy"] = False
     out["show_nav_strategy_records"] = False
     out["show_nav_system_guide"] = False
+    out["show_settings_options_swap"] = False
     return out
 
 
@@ -140,7 +141,6 @@ def display_meta_for_ui() -> list[dict[str, Any]]:
         "show_settings_transfer",
         "show_settings_export",
         "show_settings_password",
-        "show_settings_options_swap",
         "show_settings_options_transfer",
     ]
     return [