chore(core): change audio transcription job to use gemini 2.5 pro (#13202)

#### PR Dependency Tree


* **PR #13202** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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

* **New Features**
* Improved the "Transcript audio" text action by updating its default AI
model to "gemini-2.5-pro" for enhanced performance.
* Enhanced audio transcription accuracy by refining audio content
handling with a more specific audio format.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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Co-authored-by: DarkSky <darksky2048@gmail.com>

packages/backend/server/src/plugins/copilot/prompt/prompts.ts

@@ -303,7 +303,7 @@ const textActions: Prompt[] = [
   {
     name: 'Transcript audio',
     action: 'Transcript audio',
-    model: 'gemini-2.5-flash',
+    model: 'gemini-2.5-pro',
     optionalModels: ['gemini-2.5-flash', 'gemini-2.5-pro'],
     messages: [
       {