Deleting and Favoriting Contacts

Favoriting a contact is a one-click, no-confirmation action — a plain
Server Action form is enough, and it needs zero client-side JavaScript.

Deleting is different: it’s destructive, so it needs a confirmation dialog
before it fires. That confirmation has to run in the browser, which means
this is the one place in the whole app that genuinely needs a Client
Component.

Building both back to back makes the distinction concrete instead of
abstract.