fix(hub,gate): cross-margin TP/SL and dedupe hub conditional orders

Gate hedge position triggers use close=false; stop silent ccxt fallback on cross margin. Hub merges agent and Flask TP/SL by trigger price and labels Gate orders correctly.

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

crypto_monitor_gate_bot/app.py

@@ -3120,16 +3120,32 @@ def _gate_place_stop_loss_only_position(exchange_symbol, direction, stop_loss):
     raise RuntimeError(f"交易所未接受仅止损仓位触发单：{last_err}")
 
 
+def _gate_td_mode_is_cross():
+    return _GATE_DEFAULT_MARGIN_MODE == "cross"
+
+
 def _gate_place_tp_sl_orders(exchange_symbol, direction, contracts_amount, stop_loss, take_profit):
+    pos_err = None
     if GATE_TPSL_USE_POSITION_ORDER:
         try:
             _gate_place_tp_sl_orders_position_price_orders(exchange_symbol, direction, stop_loss, take_profit)
             return
-        except Exception:
-            pass
-    _gate_place_tp_sl_orders_legacy_conditional(
-        exchange_symbol, direction, contracts_amount, stop_loss, take_profit,
-    )
+        except Exception as e:
+            pos_err = e
+            if _gate_td_mode_is_cross():
+                raise RuntimeError(
+                    f"交易所未接受仓位类条件止盈/止损（全仓不支持 ccxt 条件单回退）：{pos_err}"
+                ) from e
+    try:
+        _gate_place_tp_sl_orders_legacy_conditional(
+            exchange_symbol, direction, contracts_amount, stop_loss, take_profit,
+        )
+    except Exception as legacy_err:
+        if pos_err is not None:
+            raise RuntimeError(
+                f"交易所未接受仓位类条件止盈/止损：{pos_err}；条件单回退亦失败：{legacy_err}"
+            ) from legacy_err
+        raise
 
 
 def ensure_markets_loaded(force=False):