Add a combined stylesheet entry for package consumers

docs/rfcs/multi-style-architecture.md

@@ -546,7 +546,7 @@ Deliverables:
 
 Status:
 
-- not started
+- completed
 
 ## Acceptance Criteria For The First Real Milestone
 
@@ -609,6 +609,9 @@ As of 2026-03-20, the project is at this point:
 - scoped `data-motion="reduced"` now works for nested docs wrappers
 - shared skin-aware treatment now extends across the broader component library surface,
   including controls, menus, overlays, feedback, and data-heavy patterns
+- package consumers can now import a single combined stylesheet from
+  `@ai-ui/ui/styles.css`
 
-The next implementation task should be Phase 5: improve packaging and consumer
-ergonomics for style consumption.
+The original Phase 0-5 implementation sequence is now complete. Further work should be
+treated as iteration: refining skins, expanding motion packs, or hardening package and
+registry distribution.