Platform admins can now cleanly remove a customer org (account ends) or a stray
workspace from the UI, instead of raw SQL that risks orphaning resources.
The tenant cascade isn't pure DB CASCADE - workspace-scoped tables (devices,
content, playlists, ...) are NO ACTION and must be purged before the workspace.
Extracted that logic out of deleteUserCascade into shared deleteWorkspaceCascade /
deleteOrgCascade helpers (one tested implementation; deleteUserCascade now reuses
the purgeWorkspaces extraction).
Backend (platform-admin only): GET /api/admin/orgs (list + owner + counts +
workspaces), DELETE /api/admin/orgs/:id, DELETE /api/admin/workspaces/:id.
UI: an Organizations section in Admin listing every org/workspace with a
type-the-name confirmation before the irreversible delete.
Tests: org/workspace cascade (real FKs) + endpoint gating/404. Suite 53/53.