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/providers/index.ts

@@ -1,21 +1,29 @@
-import { AnthropicProvider } from './anthropic';
+import {
+  AnthropicOfficialProvider,
+  AnthropicVertexProvider,
+} from './anthropic';
 import { FalProvider } from './fal';
-import { GeminiProvider } from './gemini';
+import { GeminiGenerativeProvider, GeminiVertexProvider } from './gemini';
 import { OpenAIProvider } from './openai';
 import { PerplexityProvider } from './perplexity';
 
 export const CopilotProviders = [
   OpenAIProvider,
   FalProvider,
-  GeminiProvider,
+  GeminiGenerativeProvider,
+  GeminiVertexProvider,
   PerplexityProvider,
-  AnthropicProvider,
+  AnthropicOfficialProvider,
+  AnthropicVertexProvider,
 ];
 
-export { AnthropicProvider } from './anthropic';
+export {
+  AnthropicOfficialProvider,
+  AnthropicVertexProvider,
+} from './anthropic';
 export { CopilotProviderFactory } from './factory';
 export { FalProvider } from './fal';
-export { GeminiProvider } from './gemini';
+export { GeminiGenerativeProvider, GeminiVertexProvider } from './gemini';
 export { OpenAIProvider } from './openai';
 export { PerplexityProvider } from './perplexity';
 export type { CopilotProvider } from './provider';