feat(server): switch i2i to gpt (#12238)

fix AI-14
fix AI-17
fix AI-39
fix AI-112

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

- **New Features**
  - Expanded and reorganized prompt options for text and image actions, adding new prompts for image generation, style conversions, upscaling, background removal, and sticker creation.
  - Enhanced image editing capabilities with direct support for image attachments in prompts.

- **Improvements**
  - Updated prompt names and descriptions to be more user-friendly and descriptive.
  - Simplified and clarified prompt selection and image processing workflows with improved default behaviors.
  - Better organization of prompts through clear grouping and categorization.

- **Bug Fixes**
  - Improved validation and handling of image attachments during editing requests.

- **Refactor**
  - Internal code restructuring of prompts and provider logic for clarity and maintainability without affecting user workflows.
  - Refined message handling and content merging logic to ensure consistent prompt processing.
  - Adjusted image attachment rendering logic for improved display consistency.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/copilot.e2e.ts

@@ -543,12 +543,19 @@ test('should be able to chat with special image model', async t => {
     );
   };
 
-  await testWithModel('debug:action:fal-sd15', 'some-tag');
+  await testWithModel('Generate image', 'some-tag');
   await testWithModel(
-    'debug:action:fal-upscaler',
-    'best quality, 8K resolution, highres, clarity, some-tag'
+    'Convert to sticker',
+    'convert this image to sticker. you need to identify the subject matter and warp a circle of white stroke around the subject matter and with transparent background. some-tag'
+  );
+  await testWithModel(
+    'Upscale image',
+    'make the image more detailed. some-tag'
+  );
+  await testWithModel(
+    'Remove background',
+    'Keep the subject and remove other non-subject items. Transparent background. some-tag'
   );
-  await testWithModel('debug:action:fal-remove-bg', 'some-tag');
 
   Sinon.restore();
 });