Add leanchecker kernel-level validation step to CI build job

Co-Authored-By: Claude <noreply@anthropic.com>

Author: SnO2WMaN

.github/workflows/ci.yml

@@ -47,6 +47,9 @@ jobs:
       - name: Build ProvabilityLogic
         run: lake build ProvabilityLogic
 
+      - name: Check environment with leanchecker
+        run: lake env leanchecker ProvabilityLogic
+
       - name: Pack project cache
         run: lake pack
       - name: Save project cache