feat: KB 列表返回 coverUrl（coverKey → 预签名下载URL）

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

src/modules/knowledge-base/knowledge-base.service.ts

@@ -2,6 +2,7 @@ import { Injectable, BadRequestException, NotFoundException, ForbiddenException,
 import { KnowledgeBaseRepository } from './knowledge-base.repository';
 import { PrismaService } from '../../infrastructure/database/prisma.service';
 import { ContentSafetyService } from '../content-safety/content-safety.service';
+import { StorageService } from '../../infrastructure/storage/storage.service';
 import { MAX_KNOWLEDGE_BASE_COUNT } from './constants/knowledge-base.constants';
 
 @Injectable()
@@ -9,6 +10,7 @@ export class KnowledgeBaseService {
   constructor(
     private readonly repository: KnowledgeBaseRepository,
     private readonly prisma: PrismaService,
+    private readonly storage: StorageService,
     @Optional() private readonly safety?: ContentSafetyService,
   ) {}
 
@@ -21,11 +23,25 @@ export class KnowledgeBaseService {
       const check = await this.safety?.check(dto.title, { userId, contentType: 'kb-title' });
       if (check && !check.safe) throw new ForbiddenException('知识库名称包含违规内容');
     }
-    return this.repository.create(userId, dto);
+    return this.enrichWithCoverUrl(await this.repository.create(userId, dto));
   }
 
   async findAll(userId: string, pagination: { page?: number; limit?: number }) {
-    return this.repository.findAllByUserId(userId, pagination);
+    const kbs = await this.repository.findAllByUserId(userId, pagination);
+    return Promise.all(kbs.map(kb => this.enrichWithCoverUrl(kb)));
+  }
+
+  private async enrichWithCoverUrl(kb: any) {
+    if (kb.coverKey) {
+      try {
+        kb.coverUrl = await this.storage.getDownloadUrl(kb.coverKey, 86400);
+      } catch {
+        kb.coverUrl = null;
+      }
+    } else {
+      kb.coverUrl = null;
+    }
+    return kb;
   }
 
   async findOne(userId: string, id: string) {