chore(server): add detail for error (#13151)

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

* **New Features**
* Error messages for unavailable copilot providers now include specific
model IDs for clearer context.
* Added new detailed error messages for embedding generation failures
specifying provider and error details.
* The API and GraphQL schema have been extended with new error types
reflecting these detailed error cases.

* **Bug Fixes**
* Enhanced error handling to detect and report incomplete or missing
embeddings from providers.
* Added safeguards to skip embedding insertions when no embeddings are
provided, preventing unnecessary processing.

* **Documentation**
* Updated localization and translation keys to support dynamic error
messages with model IDs and provider details.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/copilot/embedding/client.ts

@@ -5,6 +5,7 @@ import {
   CopilotPromptNotFound,
   CopilotProviderNotSupported,
 } from '../../../base';
+import { CopilotFailedToGenerateEmbedding } from '../../../base/error/errors.gen';
 import { ChunkSimilarity, Embedding } from '../../../models';
 import { PromptService } from '../prompt';
 import {
@@ -74,6 +75,12 @@ class ProductionEmbeddingClient extends EmbeddingClient {
       input,
       { dimensions: EMBEDDING_DIMENSIONS }
     );
+    if (embeddings.length !== input.length) {
+      throw new CopilotFailedToGenerateEmbedding({
+        provider: provider.type,
+        message: `Expected ${input.length} embeddings, got ${embeddings.length}`,
+      });
+    }
 
     return Array.from(embeddings.entries()).map(([index, embedding]) => ({
       index,