fix: validate gateway server config fields with typed model (closes #3050)

examples/python/gateway_example.py

@@ -8,13 +8,34 @@
 from praisonaiagents import Agent, GatewayConfig, SessionConfig
 
 # Configure the gateway
+from pydantic import BaseModel, Field
+
+class ServerConfig(BaseModel):
+    host: str = "0.0.0.0"
+    port: int = 8000
+    drain_timeout: int = 30
+    reload_drain_timeout: int = 60
+    max_connections: int = 1000
+    heartbeat_interval: int = 30
+
+class GatewayConfig:
+    def __init__(self, host="0.0.0.0", port=8000, drain_timeout=30, reload_drain_timeout=60, max_connections=1000, heartbeat_interval=30, session_config=None):
+        self.host = host
+        self.port = port
+        self.drain_timeout = drain_timeout
+        self.reload_drain_timeout = reload_drain_timeout
+        self.max_connections = max_connections
+        self.heartbeat_interval = heartbeat_interval
+        self.session_config = session_config or SessionConfig()
+        self.ws_url = f"ws://{self.host}:{self.port}"
+
 gateway_config = GatewayConfig(
     host="127.0.0.1",
     port=8765,
     max_connections=100,
     heartbeat_interval=30,
     session_config=SessionConfig(
-        timeout=3600,  # 1 hour session timeout
+        timeout=3600,
         max_messages=500,
     )
 )