feat: implement QuestionBank CRUD with pagination and template query

- Add pagination support to findAll (page, limit query params)
- Add findByTemplateId method to service
- Add GET /by-template/:templateId endpoint to controller
- Service already includes CRUD for QuestionBank and QuestionBankItem

server/src/ai/ai.module.ts

@@ -0,0 +1,8 @@
+import { Module } from '@nestjs/common';
+import { EmbeddingService } from './embedding.service';
+
+@Module({
+  providers: [EmbeddingService],
+  exports: [EmbeddingService],
+})
+export class AiModule {}

server/src/ai/embedding.service.ts

@@ -0,0 +1,29 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { OpenAIEmbeddings } from '@langchain/openai';
+import { ModelConfig } from '../model-config/model-config.entity';
+
+@Injectable()
+export class EmbeddingService {
+  private readonly logger = new Logger(EmbeddingService.name);
+
+  async getEmbeddings(text: string, config: ModelConfig): Promise<number[]> {
+    try {
+      const embeddings = new OpenAIEmbeddings({
+        openAIApiKey: config.apiKey || 'ollama',
+        configuration: {
+          baseURL: config.baseUrl,
+        },
+        modelName: config.modelId,
+      });
+
+      const vector = await embeddings.embedQuery(text);
+      return vector;
+    } catch (error) {
+      this.logger.error(
+        `Failed to generate embeddings using model ${config.modelId}`,
+        error,
+      );
+      throw error;
+    }
+  }
+}