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/embedding/client.ts

@@ -15,6 +15,10 @@ import {
 import { PromptService } from '../prompt/service';
 import { CopilotProviderFactory } from '../providers/factory';
 import type { CopilotProvider } from '../providers/provider';
+import {
+  DEFAULT_RERANK_MODEL,
+  normalizeRerankModel,
+} from '../providers/rerank';
 import {
   type ModelFullConditions,
   ModelInputType,
@@ -114,10 +118,16 @@ class ProductionEmbeddingClient extends EmbeddingClient {
     if (!prompt) {
       throw new CopilotPromptNotFound({ name: RERANK_PROMPT });
     }
-    const provider = await this.getProvider({ modelId: prompt.model });
+    const rerankModel = normalizeRerankModel(prompt.model);
+    if (prompt.model !== rerankModel) {
+      this.logger.warn(
+        `Unsupported rerank model "${prompt.model}" configured, falling back to "${DEFAULT_RERANK_MODEL}".`
+      );
+    }
+    const provider = await this.getProvider({ modelId: rerankModel });
 
     const ranks = await provider.rerank(
-      { modelId: prompt.model },
+      { modelId: rerankModel },
       embeddings.map(e => prompt.finish({ query, doc: e.content })),
       { signal }
     );
@@ -171,7 +181,7 @@ class ProductionEmbeddingClient extends EmbeddingClient {
     );
 
     try {
-      // 4.1 mini's context windows large enough to handle all embeddings
+      // The rerank prompt is expected to handle the full deduped candidate list.
       const ranks = await this.getEmbeddingRelevance(
         query,
         sortedEmbeddings,