feat(client): add Card header/footer, DescriptionList, and portal ContextMenu

- add Card header prop (primary/secondary variants) and footer prop (sticks to bottom)
- add Breadcrumbs to all 5 pages; remove duplicate h1 headings
- add pageToolbar layout for breadcrumbs + danger button aligned right
- add DescriptionList component replacing raw dl/dt/dd markup; supports truncate+tooltip
- rewrite ContextMenu to render dropdown via React portal to avoid clip/overflow issues
- update EnvironmentCard to use Card header (primary), footer (Timestamp), and truncated DescriptionList
- fix cog button contrast, square sizing, and right-edge alignment on colored header
- add border to Timestamp pill for dark-mode visibility
- add id badge pill styling to environment card header

client/src/ui/index.ts

@@ -30,5 +30,8 @@ export type { PaginationProps } from './Pagination/Pagination';
 export { ContextMenu } from './ContextMenu/ContextMenu';
 export type { ContextMenuProps, ContextMenuItem } from './ContextMenu/ContextMenu';
 
+export { DescriptionList } from './DescriptionList/DescriptionList';
+export type { DescriptionListProps, DescriptionListItem } from './DescriptionList/DescriptionList';
+
 export { Table } from './Table/Table';
 export type { TableProps, TableColumn } from './Table/Table';