fix: Update release workflow to support immutable releases

Changed from softprops/action-gh-release to native gh CLI command.
This creates the release and uploads assets in one atomic operation,
which works correctly with GitHub's immutable releases setting.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: GeneAI

.github/workflows/release.yml

@@ -66,15 +66,14 @@ jobs:
         echo "**Full Changelog**: https://github.com/${{ github.repository }}/compare/$(git describe --tags --abbrev=0 HEAD^)...v${{ steps.version.outputs.version }}" >> RELEASE_NOTES.md
 
     - name: Create GitHub Release
-      uses: softprops/action-gh-release@v1
-      with:
-        body_path: RELEASE_NOTES.md
-        files: dist/*
-        draft: false
-        prerelease: false
-        generate_release_notes: true
       env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: |
+        gh release create v${{ steps.version.outputs.version }} \
+          dist/* \
+          --title "v${{ steps.version.outputs.version }}" \
+          --notes-file RELEASE_NOTES.md \
+          --verify-tag
 
     - name: Publish to PyPI
       if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/')