The embarrassingly simple answer to embedding ANY Javascript and HTML into a Kibana vis is to hack the markdown_vis plugin to not use markdown at all, but just display the HTML as-is.

Modify src/plugins/markdown_vis/public/markdown_vis_controller.js, and comment out

 

and replace it with

 

You'll need to recreate the bundles (just install or remove/reinstall sense for example) and restart Kibana for this to take effect. It's pretty awesome, because now the sky's the limit!