fix: frontend missing components - proxy build sukses

- Hapus export DetailStat dan StatCard dari shared/index.ts
  (file komponen tidak ada atau salah lokasi)
- Buat message-detail-view.tsx dengan export MessageDetailView
  (rename dari message-detail.tsx, sesuaikan export name)

Proxy image 96.9MB (nginx:alpine + 3.1MB static export)

services/frontend/src/components/shared/index.ts

@@ -1,6 +1,4 @@
-export { DetailStat } from "./detail-stat";
 export { EmptyState } from "./empty-state";
 export { ErrorBoundary } from "./error-boundary";
 export { ErrorState } from "./error-state";
 export { LoadingSkeleton } from "./loading-skeleton";
-export { StatCard } from "./stat-card";