Prototype ConfigKit and PromptKit adoption and record the findings

docs/roadmap/configkit.md

@@ -25,6 +25,10 @@ supported release and current conventions during detailed planning. The installe
 application must depend on a versioned module, not a sibling checkout or local
 module replacement.
 
+The shared boundary/prototype unit is complete. Its [selected contract, inventory,
+and implementation handoff](library-boundary-findings.md) refine the provisional
+directions here; production configuration migration has not begun.
+
 ## Proposed End State
 
 - ConfigKit owns strict YAML loading, input presence, default application, explicit