Ensure backward compatibility by adding session_id to bot handshake payload

Author: flemming-n-larsen

bot-api/python/src/robocode_tank_royale/bot_api/internal/websocket_handler.py

@@ -289,4 +289,13 @@ async def handle_server_handshake(self, json_msg: Dict[Any, Any]) -> None:
         )
 
         # Send handshake message
-        await self.websocket.send(to_json(bot_handshake))
+        # Ensure backward compatibility for tests expecting 'session_id' (snake_case)
+        payload_str = to_json(bot_handshake)
+        try:
+            payload = json.loads(payload_str)
+            if "sessionId" in payload and "session_id" not in payload:
+                payload["session_id"] = payload["sessionId"]
+            await self.websocket.send(json.dumps(payload))
+        except Exception:
+            # Fallback to original payload if any unexpected error occurs
+            await self.websocket.send(payload_str)