debug: verify harness file exists after build

Author: Hweinstock

.github/workflows/strands-command.yml

@@ -115,6 +115,9 @@ jobs:
           npm run build
           npm run build:harness
           npm install -g "$(npm pack | tail -1)"
+          echo "--- Verifying harness exists ---"
+          ls -la dist/mcp-harness/index.mjs
+          node -e "require('fs').accessSync('${{ github.workspace }}/dist/mcp-harness/index.mjs'); console.log('File accessible')"
 
       - name: Set MCP harness path
         if: steps.process-inputs.outputs.mode == 'tester'