ci: attach built JARs to GitHub Release on tag push

Add a github-release job that downloads the llama-jars artifact produced
by the package job and uploads them to the GitHub Release via
softprops/action-gh-release. Runs only when a v* tag is pushed,
after publish-release completes successfully.

Author: bernardladenthin

.github/workflows/publish.yml

@@ -656,6 +656,23 @@ jobs:
           MAVEN_PASSWORD: ${{ secrets.CENTRAL_TOKEN }}
           MAVEN_GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
 
+  github-release:
+    name: Attach Binaries to GitHub Release
+    needs: [publish-release]
+    if: startsWith(github.ref, 'refs/tags/v')
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/download-artifact@v8
+        with:
+          name: llama-jars
+          path: release-assets/
+      - name: Upload release assets
+        uses: softprops/action-gh-release@v2
+        with:
+          files: release-assets/*
+
   post-publish:
     name: Post-Publish
     needs: [package, publish-snapshot, publish-release]