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/__tests__/mocks/copilot.mock.ts

@@ -39,33 +39,6 @@ export class MockCopilotProvider extends OpenAIProvider {
         },
       ],
     },
-    {
-      id: 'gpt-4o',
-      capabilities: [
-        {
-          input: [ModelInputType.Text, ModelInputType.Image],
-          output: [ModelOutputType.Text, ModelOutputType.Object],
-        },
-      ],
-    },
-    {
-      id: 'gpt-4o-2024-08-06',
-      capabilities: [
-        {
-          input: [ModelInputType.Text, ModelInputType.Image],
-          output: [ModelOutputType.Text, ModelOutputType.Object],
-        },
-      ],
-    },
-    {
-      id: 'gpt-4.1-2025-04-14',
-      capabilities: [
-        {
-          input: [ModelInputType.Text, ModelInputType.Image],
-          output: [ModelOutputType.Text, ModelOutputType.Object],
-        },
-      ],
-    },
     {
       id: 'gpt-5',
       capabilities: [
@@ -97,6 +70,19 @@ export class MockCopilotProvider extends OpenAIProvider {
         },
       ],
     },
+    {
+      id: 'gpt-5-nano',
+      capabilities: [
+        {
+          input: [ModelInputType.Text, ModelInputType.Image],
+          output: [
+            ModelOutputType.Text,
+            ModelOutputType.Object,
+            ModelOutputType.Structured,
+          ],
+        },
+      ],
+    },
     {
       id: 'gpt-image-1',
       capabilities: [
@@ -133,6 +119,23 @@ export class MockCopilotProvider extends OpenAIProvider {
         },
       ],
     },
+    {
+      id: 'gemini-3.1-pro-preview',
+      capabilities: [
+        {
+          input: [
+            ModelInputType.Text,
+            ModelInputType.Image,
+            ModelInputType.Audio,
+          ],
+          output: [
+            ModelOutputType.Text,
+            ModelOutputType.Object,
+            ModelOutputType.Structured,
+          ],
+        },
+      ],
+    },
   ];
 
   override async text(