feat(core): add google vertex ai (#12423)

Close [AI-125](https://linear.app/affine-design/issue/AI-125)

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

- **New Features**
  - Added new provider configurations `geminiVertex` and `anthropicVertex` for Google Vertex AI in backend schema, provider classes, and admin config.
  - Introduced `GeminiVertexProvider` and `AnthropicVertexProvider` classes supporting Vertex AI models with specific capabilities.
  - Expanded model options for transcription prompts with newer Gemini models.
  - Re-exported provider modules to include Vertex AI variants.

- **Improvements**
  - Extended provider architecture to support separate Vertex AI configurations and models.
  - Updated test setup to replace deprecated provider references with new Vertex variants.
  - Consolidated environment variables for server testing with a single `SERVER_CONFIG`.

- **Bug Fixes**
  - Updated mock models and import references in tests to align with new provider classes.

- **Chores**
  - Added `@ai-sdk/google-vertex` dependency for Vertex AI support.
  - Updated dependency list to include `@ai-sdk/google-vertex`.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -350,7 +350,7 @@ const actions: Prompt[] = [
   {
     name: 'Transcript audio',
     action: 'Transcript audio',
-    model: 'gemini-2.5-pro-preview-05-06',
+    model: 'gemini-2.5-flash-preview-05-20',
     messages: [
       {
         role: 'system',
@@ -1096,8 +1096,12 @@ const chat: Prompt[] = [
       'o4-mini',
       'claude-3-7-sonnet-20250219',
       'claude-3-5-sonnet-20241022',
-      'gemini-2.5-flash-preview-04-17',
+      'gemini-2.5-flash-preview-05-20',
       'gemini-2.5-pro-preview-05-06',
+      'claude-opus-4@20250514',
+      'claude-sonnet-4@20250514',
+      'claude-3-7-sonnet@20250219',
+      'claude-3-5-sonnet@20240620',
     ],
     messages: [
       {