Admins can edit and route platform notifications

Previously, managing platform announcements and changelogs lacked fine-grained control, and changelog visibility was not strictly bound to specific user contexts.

Administrators can now fully edit, delete, archive, and instantly publish platform notifications from the webapp interface. In tandem, changelog fetching has been overhauled to actively verify organization and project membership.

This gives the team deep control over the notification lifecycle while ensuring users only see updates directly relevant to their current active workspaces. By restricting queries to validated scopes, the system securely prevents cross-tenant data leakage and actively suppresses announcements scheduled for the future.