Fix Helion system_prompt: correct payload.context structure

Changed from nested 'payload': {'context': {
to proper 'payload': { 'context': { structure
so Router can extract system_prompt correctly

gateway-bot/http_api.py

@@ -463,11 +463,12 @@ async def helion_telegram_webhook(update: TelegramUpdate):
                 "username": username,
                 "chat_id": chat_id,
             },
-            "payload": {"context": {
+            "payload": {
+                "context": {
                     "agent_name": HELION_NAME,
                     "system_prompt": HELION_SYSTEM_PROMPT,
                     "memory": memory_context,
-            },
+                }
             },
         }