chore(server): update config naming (#13419)

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

* **New Features**
* Updated scenario names and options for Copilot, including new and
renamed scenarios such as "audio_transcribing,"
"complex_text_generation," "quick_decision_making,"
"quick_text_generation," and "polish_and_summarize."
* Enhanced support for customizing and overriding default model
assignments in Copilot scenarios.

* **Bug Fixes**
* Improved consistency and clarity in scenario configuration and prompt
selection.

* **Documentation**
* Updated descriptions in configuration interfaces to better explain the
ability to use custom models and override defaults.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -117,13 +117,13 @@ test.serial.before(async t => {
       value: {
         enabled: true,
         scenarios: {
-          image: 'lcm',
+          image: 'flux-1/schnell',
           rerank: 'gpt-4.1-mini',
-          brainstorm: 'gpt-4.1-mini',
+          complex_text_generation: 'gpt-4.1-mini',
           coding: 'gpt-4.1-mini',
-          quick_decision: 'gpt-4.1-mini',
-          quick_written: 'gpt-4.1-mini',
-          summary_inspection: 'gemini-2.5-flash',
+          quick_decision_making: 'gpt-4.1-mini',
+          quick_text_generation: 'gpt-4.1-mini',
+          polish_and_summarize: 'gemini-2.5-flash',
         },
       },
     },