- Add _EmbeddingFunctionWrapper class with __call__(self, input) signature
- Use ThreadPoolExecutor to run async embed in isolated thread with fresh event loop
- Fixes asyncio.run() cannot be called from a running event loop
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>