Add explicit error handling for SAM build artifacts

- Add verification step to check .aws-sam directory exists after build
- Add if-no-files-found: error to fail explicitly if artifacts are missing

Author: smessmer

.github/workflows/backend.yml

@@ -35,11 +35,17 @@ jobs:
       - name: Build
         working-directory: backend
         run: npm run build
+      - name: Verify build output
+        run: |
+          echo "Checking for .aws-sam directory..."
+          ls -la backend/
+          ls -la backend/.aws-sam/ || echo "ERROR: .aws-sam directory not found!"
       - name: Store artifacts
         uses: actions/upload-artifact@v4
         with:
           name: sam-build
           path: backend/.aws-sam
+          if-no-files-found: error
 
   deploy:
     needs: build