feat(#69): implement embedding generation pipeline

Generate embeddings for knowledge entries using Ollama via BullMQ job queue.

Changes:
- Created OllamaEmbeddingService for Ollama-based embedding generation
- Set up BullMQ queue and processor for async embedding jobs
- Integrated queue into knowledge entry lifecycle (create/update)
- Added rate limiting (1 job/second) and retry logic (3 attempts)
- Added OLLAMA_EMBEDDING_MODEL environment variable configuration
- Implemented dimension normalization (padding/truncating to 1536 dimensions)
- Added graceful degradation when Ollama is unavailable

Test Coverage:
- All 31 embedding-related tests passing
- ollama-embedding.service.spec.ts: 13 tests
- embedding-queue.spec.ts: 6 tests
- embedding.processor.spec.ts: 5 tests
- Build and linting successful

Fixes #69

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/knowledge/knowledge.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, NotFoundException, ConflictException } from "@nestjs/common";
+import { Injectable, NotFoundException, ConflictException, Logger } from "@nestjs/common";
 import { EntryStatus, Prisma } from "@prisma/client";
 import slugify from "slugify";
 import { PrismaService } from "../prisma/prisma.service";
@@ -12,17 +12,23 @@ import { renderMarkdown } from "./utils/markdown";
 import { LinkSyncService } from "./services/link-sync.service";
 import { KnowledgeCacheService } from "./services/cache.service";
 import { EmbeddingService } from "./services/embedding.service";
+import { OllamaEmbeddingService } from "./services/ollama-embedding.service";
+import { EmbeddingQueueService } from "./queues/embedding-queue.service";
 
 /**
  * Service for managing knowledge entries
  */
 @Injectable()
 export class KnowledgeService {
+  private readonly logger = new Logger(KnowledgeService.name);
+
   constructor(
     private readonly prisma: PrismaService,
     private readonly linkSync: LinkSyncService,
     private readonly cache: KnowledgeCacheService,
-    private readonly embedding: EmbeddingService
+    private readonly embedding: EmbeddingService,
+    private readonly ollamaEmbedding: OllamaEmbeddingService,
+    private readonly embeddingQueue: EmbeddingQueueService
   ) {}
 
   /**
@@ -851,14 +857,22 @@ export class KnowledgeService {
   /**
    * Generate and store embedding for a knowledge entry
    * Private helper method called asynchronously after entry create/update
+   * Queues the embedding generation job instead of processing synchronously
    */
   private async generateEntryEmbedding(
     entryId: string,
     title: string,
     content: string
   ): Promise<void> {
-    const combinedContent = this.embedding.prepareContentForEmbedding(title, content);
-    await this.embedding.generateAndStoreEmbedding(entryId, combinedContent);
+    const combinedContent = this.ollamaEmbedding.prepareContentForEmbedding(title, content);
+
+    try {
+      const jobId = await this.embeddingQueue.queueEmbeddingJob(entryId, combinedContent);
+      this.logger.log(`Queued embedding job ${jobId} for entry ${entryId}`);
+    } catch (error) {
+      this.logger.error(`Failed to queue embedding job for entry ${entryId}`, error);
+      throw error;
+    }
   }
 
   /**