setup-curator-cascade-required-for-new-artifact-categories

When a new artifact category is introduced to the memory system, the setup-curator cascade must touch four targets: (1) create the topic file for the new category, (2) update MEMORY.md in multiple sections (Skill & Plugin Gate, Pruning Principle, Topic Files index), (3) update the setup-curator SKILL.md routing tree, and (4) remove or migrate any superseded copies of the artifact. Skipping any leg leaves the routing tree inconsistent and future sessions will miss the category.