fix(prod): resolve middleware piping error and AI model ID

patches/@mintel__payload-ai@1.9.15.patch

@@ -129,3 +129,16 @@ index 9081ae77d4eae53ce660e285c1a6babde99ceaab..f262f1dd0fd1199734024cc27905d956
  
  export const ChatWindowProvider: React.FC<{ children: React.ReactNode }> = ({ children }) => {
      return (
+
+diff --git a/dist/endpoints/chatEndpoint.js b/dist/endpoints/chatEndpoint.js
+--- a/dist/endpoints/chatEndpoint.js
++++ b/dist/endpoints/chatEndpoint.js
+@@ -50,7 +50,7 @@
+     try {
+         const result = streamText({
+             // @ts-ignore - AI SDK type mismatch
+-            model: openrouter('google/gemini-3.0-flash'),
++            model: openrouter('google/gemini-3.1-flash-lite-preview'),
+             messages,
+             tools: activeTools,
+             system: `You are a helpful Payload CMS MCP Assistant orchestrating the local Mintel ecosystem.