ci: Upload build artifacts in CI

This commit updates the `build-desktop.yml` GitHub Actions workflow to upload the generated application packages as build artifacts.

-   Adds an `actions/upload-artifact@v4` step.
-   Configures the step to upload the build output from `composeApp/build/compose/binaries/` for each matrix format (`.dmg`, `.msi`, `.deb`, etc.).

Author: Coding-Meet

.github/workflows/build-desktop.yml

@@ -45,6 +45,12 @@ jobs:
       - name: Check build output
         run: ls -R composeApp/build/compose/binaries || true
 
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: build-${{ matrix.format }}
+          path: composeApp/build/compose/binaries/**/${{ matrix.format }}/
+
       - name: Upload to GitHub Release
         uses: softprops/action-gh-release@v2
         if: startsWith(github.ref, 'refs/tags/')