add artifact gathering

.github/workflows/windows.yaml

@@ -27,3 +27,10 @@ jobs:
 
     - name: Build for Windows
       run: flutter build windows
+
+    - name: Gather artifacts
+      uses: actions/upload-artifact@v4
+      with:
+        name: flutter-windows-build-latest
+        path: build
+        if-no-files-found: error