feat(ui): require confirmation before delete actions

- add a reusable modal component and export it from the shared ui barrel

- gate all delete and remove flows behind explicit confirmation dialogs

- use a solid modal surface color token with fallback to avoid transparent body

client/src/ui/index.ts

@@ -57,6 +57,9 @@ export type { DescriptionListProps, DescriptionListItem } from './DescriptionLis
 export { Notification } from './Notification/Notification';
 export type { NotificationProps, NotificationVariant } from './Notification/Notification';
 
+export { Modal } from './Modal/Modal';
+export type { ModalProps } from './Modal/Modal';
+
 export { Table } from './Table/Table';
 export type { TableProps, TableColumn } from './Table/Table';