feat(server): adapt gemini3.1 preview (#14583)

#### PR Dependency Tree


* **PR #14583** 👈

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**
* Added Gemini 3.1 Pro Preview support (text, image, audio) and new
GPT‑5 variants as defaults; centralized persistent telemetry state for
more reliable client identity.

* **UX**
  * Improved model submenu placement in chat preferences.
* More robust mindmap parsing, preview, regeneration and replace
behavior.

* **Chores**
  * Bumped AI SDK and related dependencies.

* **Tests**
  * Expanded/updated tests and increased timeouts for flaky flows.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -230,9 +230,8 @@ defineModuleConfig('copilot', {
         chat: 'gemini-2.5-flash',
         embedding: 'gemini-embedding-001',
         image: 'gpt-image-1',
-        rerank: 'gpt-4.1',
         coding: 'claude-sonnet-4-5@20250929',
-        complex_text_generation: 'gpt-4o-2024-08-06',
+        complex_text_generation: 'gpt-5-mini',
         quick_decision_making: 'gpt-5-mini',
         quick_text_generation: 'gemini-2.5-flash',
         polish_and_summarize: 'gemini-2.5-flash',