fix: revert to reliable artifact upload

Revert from Debian Package Registry API (404 errors) back to
proven artifact upload method. Update README with clear
download instructions for Actions artifacts.

.forgejo/workflows/build-libostree-backport.yml

@@ -133,32 +133,9 @@ jobs:
           echo "" >> release-assets/INSTALL.md
           echo "Build completed on: $(date)" >> release-assets/INSTALL.md
 
-      - name: Install curl for package upload
-        run: |
-          apt-get update -y
-          apt-get install -y curl
-
-      - name: Upload to Debian Package Registry
-        run: |
-          # Upload each .deb package to Forgejo's Debian Package Registry
-          for deb_file in release-assets/*.deb; do
-            if [ -f "$deb_file" ]; then
-              echo "Uploading $deb_file to Debian Package Registry..."
-              # Extract package name and version
-              pkg_name=$(dpkg-deb -f "$deb_file" Package)
-              pkg_version=$(dpkg-deb -f "$deb_file" Version)
-              pkg_arch=$(dpkg-deb -f "$deb_file" Architecture)
-              
-              echo "Package: $pkg_name"
-              echo "Version: $pkg_version"
-              echo "Architecture: $pkg_arch"
-              
-              # Upload to Forgejo's Debian Package Registry
-              # This will be available at: https://git.raines.xyz/api/packages/robojerk/debian
-              curl -X POST \
-                -H "Authorization: token ${{ secrets.GITEA_TOKEN }}" \
-                -H "Content-Type: application/vnd.debian.binary-package" \
-                --data-binary "@$deb_file" \
-                "https://git.raines.xyz/api/packages/robojerk/debian/$pkg_name/$pkg_version/$pkg_arch"
-            fi
-          done 
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: libostree-packages
+          path: release-assets/
+          retention-days: 90