Add debug step to verify workflow start

Author: HaplessIdiot

.github/workflows/cmake-multi-platform.yml

@@ -17,6 +17,8 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:
+      - name: Debug: prove workflow starts
+  run: echo "Workflow started successfully"
       - name: Checkout repository
         uses: actions/checkout@v4