Phase 1: Stabilize the Current Authoring AuthZ Experience #373

The first priority should be to stabilize what has already been started.

This includes resolving remaining Authoring issues, cleaning up waffle flag behavior, and completing the permission-aware Studio experience for restricted users.

This work reduces implementation risk and prevents the team from expanding on top of unresolved behavior.

Expected outcomes

• Authoring-specific roles, scopes, filters, and assignment flows behave correctly when the Authoring waffle flag is enabled or disabled.
• Restricted users have a coherent Studio experience.
• Hidden actions, disabled controls, empty states, and explanatory messages follow a single product rule.
• Remaining unresolved Authoring issues are listed, prioritized, and either completed or explicitly deferred.