7c777a5b27
Memory [[feedback_use_server_only_async]]: 'use server' files can only
export async functions. notification-actions.ts also exported the
NotificationActionState type and an initialNotificationActionState const,
which Next 16 now flags hard at runtime ('A "use server" file can only
export async functions, found object.').
Moved both to a sibling notification-types.ts (same pattern we already
follow for connection-types / job-file-types / prosthetic-types). The
client component imports the const from -types and the actions from
-actions; no behaviour change.