UMD in React 19

[Timeless0911]

          React 19 has removed UMD builds, see https://react.dev/blog/2024/04/25/react-19-upgrade-guide#umd-builds-removed

We use classic runtime in umd now. We should reorganize our umd examples and templates in the future.

Originally posted by @Timeless0911 in #541 (comment)