Markdown paste from Word

... picks up the wrong content type and tries to upload the picture representation.

paste handler

The paste handler is supposed to pick images from the clipboard and upload them to Genesys -- same as how gitlab works. But copy in Word (and other software) puts multiple objects on the clipboard: text/plain, text/html, etc.

The code needs to only trigger the upload in case of a real picture.

Also fix catalog-ui.