Remove incompatible with copilot responses service_tier field

Some clients, like RooCode may send `service_tier` to `/responses` endpoint, but Copilot do not support this field and returns error

Author: sr-tream

src/services/copilot/create-responses.ts

@@ -336,10 +336,13 @@ export const createResponses = async (
     "X-Initiator": initiator,
   }
 
+  // Remove service_tier from payload as it's not supported by the responses endpoint
+  const { service_tier, ...cleanPayload } = payload
+
   const response = await fetch(`${copilotBaseUrl(state)}/responses`, {
     method: "POST",
     headers,
-    body: JSON.stringify(payload),
+    body: JSON.stringify(cleanPayload),
   })
 
   if (!response.ok) {