feat(client): add Pagination component and integrate with Table and pages

- add Pagination component with prev/next, ellipsis page range, and optional page-size selector
- add Pagination and Table pagination stories (WithPagination, WithPaginationAndSizeSelector)
- extend Table with optional pageSize and pageSizeOptions props for built-in client-side pagination
- add Timestamp column to Table story fixtures
- enable pagination on all four pages with pageSize=10 and size selector
- add pagination i18n keys to en.json

client/src/pages/KeysPage.tsx

@@ -36,6 +36,8 @@ export function KeysPage() {
         rowKey={(k) => k.name}
         loading={loading}
         emptyMessage={t('keys.empty')}
+        pageSize={10}
+        pageSizeOptions={[10, 25, 50]}
       />
     </div>
   );