Companion to the calendar spec for the cross-account id-namespacing fix. Logs
in two accounts, enables the Pro shell, and asserts both accounts' address books
stay aggregated (same set, no loss/duplication/corruption) after switching the
active account. Contacts keep no persisted id-selection, so this verifies the
aggregated list stays correct/usable rather than a selection reset.
Adds a data-testid on address-book rows (address-book-item + data-book-name/
-account) and openContacts / addressBookRows helpers.