feat(server): adapt 4o image (#11956)

fix AI-88

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Added support for the new image generation model "gpt-image-1" in both backend and frontend.
  - Updated available prompt options to include "gpt-image-1" for image creation actions.

- **Improvements**
  - Set a 5-minute timeout for image generation requests to improve reliability.

- **Tests**
  - Expanded test coverage to validate image generation using the new "gpt-image-1" prompt.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/copilot-provider.spec.ts

@@ -514,7 +514,7 @@ const actions = [
     type: 'image' as const,
   },
   {
-    promptName: ['debug:action:dalle3'],
+    promptName: ['debug:action:dalle3', 'debug:action:gpt-image-1'],
     messages: [
       {
         role: 'user' as const,