fix: add upload step for build artifacts in GitHub Actions workflow

Author: guiyumin

.github/workflows/build.yml

@@ -51,3 +51,10 @@ jobs:
       - name: Build for Linux arm64
         run: |
           CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -ldflags="-s -w -X github.com/node-pulse/agent/cmd.Version=dev-${{ github.sha }}" -o dist/nodepulse-linux-arm64 .
+
+      - name: Upload build artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: nodepulse-binaries
+          path: dist/*
+          retention-days: 7