fix(frontend): api named export import 수정 (Vite 빌드 오류)

api.ts의 named export를 default import로 사용하여 Vite/Rollup 프로덕션 빌드 실패 수정

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/tabs/assets/services/assetsApi.ts

@@ -1,4 +1,4 @@
-import api from '@common/services/api';
+import { api } from '@common/services/api';
 
 // ============================================================
 // 타입

frontend/src/tabs/incidents/services/incidentsApi.ts

@@ -1,4 +1,4 @@
-import api from '@common/services/api';
+import { api } from '@common/services/api';
 
 // ============================================================
 // 백엔드 API 응답 타입