feat(server): scenario mapping (#13404)

fix AI-404

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

* **New Features**
* Introduced scenario-based configuration for copilot, allowing default
model assignments for various AI use cases.
  * Added a new image generation model to the available options.

* **Improvements**
* Refined copilot provider settings by removing deprecated fallback
options and standardizing base URL configuration.
* Enhanced prompt management to support scenario-driven updates and
improved configuration handling.
* Updated admin and settings interfaces to support new scenario
configurations.

* **Bug Fixes**
* Removed deprecated or unused prompts and related references across
platforms for consistency.

* **Other**
* Improved test coverage and updated test assets to reflect prompt and
scenario changes.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/copilot/resolver.ts

@@ -907,7 +907,7 @@ export class PromptsManagementResolver {
     @Args('messages', { type: () => [CopilotPromptMessageType] })
     messages: CopilotPromptMessageType[]
   ) {
-    await this.promptService.update(name, messages, true);
+    await this.promptService.update(name, { messages, modified: true });
     return this.promptService.get(name);
   }
 }