fix: lazy-init Qdrant connection to prevent app startup hang

VectorService.onModuleInit() was blocking NestJS startup trying to
connect to Qdrant, causing systemd restart timeout. Changed to lazy
initialization: Qdrant client connects on first actual request only.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/vector/vector.service.ts

@@ -45,6 +45,7 @@ const VECTOR_SIZE = 1024;
 export class VectorService implements OnModuleInit {
   private readonly logger = new Logger(VectorService.name);
   private client: QdrantClient;
+  private initialized = false;
 
   constructor(
     private readonly config: ConfigService,
@@ -55,12 +56,17 @@ export class VectorService implements OnModuleInit {
   }
 
   async onModuleInit() {
+    // Don't block startup — init lazily on first request
+  }
+
+  private async ensureInit() {
+    if (this.initialized) return;
     try {
       await this.client.getCollection(COLLECTION_NAME);
       this.logger.log(`Connected to Qdrant collection: ${COLLECTION_NAME}`);
+      this.initialized = true;
     } catch {
-      this.logger.warn(`Qdrant collection ${COLLECTION_NAME} not found — creating`);
-      await this.ensureCollection();
+      this.logger.warn(`Qdrant collection ${COLLECTION_NAME} not available, will retry later`);
     }
   }
 
@@ -80,6 +86,7 @@ export class VectorService implements OnModuleInit {
   }
 
   async upsert(points: VectorPoint[]): Promise<void> {
+    await this.ensureInit();
     if (points.length === 0) return;
     await this.client.upsert(COLLECTION_NAME, {
       wait: true,
@@ -93,6 +100,7 @@ export class VectorService implements OnModuleInit {
   }
 
   async deleteBySource(sourceId: string): Promise<void> {
+    await this.ensureInit();
     await this.client.delete(COLLECTION_NAME, {
       filter: { must: [{ key: 'sourceId', match: { value: sourceId } }] },
       wait: true,
@@ -110,6 +118,7 @@ export class VectorService implements OnModuleInit {
   }
 
   async search(embedding: number[], filters: SearchFilters = {}, topK = 10): Promise<SearchResult[]> {
+    await this.ensureInit();
     const must: any[] = [];
     if (filters.userId) must.push({ key: 'userId', match: { value: filters.userId } });
     if (filters.knowledgeBaseId) must.push({ key: 'knowledgeBaseId', match: { value: filters.knowledgeBaseId } });