Admin UI implementation

The admin app mounts under “Document Repository” and “Metadata Settings”. It supports PDF uploads, metadata editing, spreadsheet mode, bulk operations, status filters, and upload feedback.

• App entry: /assets/js/apps/bcew-document-repository/index.js
• Main app: /assets/js/apps/bcew-document-repository/App.js
• Styles: /assets/scss/index.scss