demo: drop design.exe --version (no --version flag; layout check suffices)

Author: scarson

.github/workflows/windows-smoke.yml

@@ -78,10 +78,11 @@ jobs:
           }
 
       - name: Smoke-test binaries
+        # design.exe's build is smoked by the layout assertion above; it
+        # doesn't implement --version, so we don't invoke it here.
         run: |
           ./browse/dist/browse.exe --version
           ./make-pdf/dist/pdf.exe --version
-          ./design/dist/design.exe --version
 
       - name: Windows-specific unit tests
         run: |