fix / correct Gateway connector import, save_pool content-type, and FastAPI redirect_slashes

main.py

@@ -305,6 +305,7 @@ async def lifespan(app: FastAPI):
     description="API for managing Hummingbot trading instances",
     version=VERSION,
     lifespan=lifespan,
+    redirect_slashes=False,
 )
 
 # Add CORS middleware

services/gateway_client.py

@@ -353,7 +353,7 @@ async def save_pool(self, chain_network: str, address: str) -> Dict:
         """Save a pool by address using GeckoTerminal lookup"""
         return await self._request("POST", f"pools/save/{address}", params={
             "chainNetwork": chain_network
-        })
+        }, json={})
 
     async def delete_pool(self, chain: str, network: str, address: str) -> Dict:
         """Delete a pool from Gateway's pool list"""

services/unified_connector_service.py

@@ -22,7 +22,7 @@
 from hummingbot.connector.connector_base import ConnectorBase
 from hummingbot.connector.connector_metrics_collector import TradeVolumeMetricCollector
 from hummingbot.connector.exchange_py_base import ExchangePyBase
-from hummingbot.connector.gateway.gateway_base import GatewayBase as Gateway
+from hummingbot.connector.gateway.gateway import Gateway
 from hummingbot.connector.perpetual_derivative_py_base import PerpetualDerivativePyBase
 from hummingbot.core.data_type.common import OrderType, PositionAction, PositionMode, TradeType
 from hummingbot.core.data_type.in_flight_order import InFlightOrder, OrderState