refactor: create model config directly via openai api to avoid issues with lookup server

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: manfredsteyer

ai-server/src/mastra/config.ts

@@ -1,10 +1,15 @@
-import type { MastraModelConfig } from '@mastra/core/llm';
+import { createOpenAI } from '@ai-sdk/openai';
+import { MastraModelConfig } from '@mastra/core/llm';
+
+const openai = createOpenAI({
+  apiKey: process.env['OPENAI_API_KEY'],
+});
 
 /**
  * Central model used by all Mastra agents in this project.
  * Change this single value to switch the model everywhere.
  */
-export const model: MastraModelConfig = 'openai/gpt-5.4-mini';
-export const modelAdvancedTasks: MastraModelConfig = 'openai/gpt-5.5';
+export const model: MastraModelConfig = openai('gpt-5.4-mini');
+export const modelAdvancedTasks: MastraModelConfig = openai('gpt-5.5');
 
-// export const model: MastraModelConfig = 'google/gemini-flash-latest'; // Gemini Flash
+// export const model: MastraModelConfig = 'google/gemini-flash-latest';