Make the video preview work in embedded mode

[jbilcke-hf]

Context

This is a mandatory feature (well this urgency is from my own perspective - so I will do it on my own time) for my Hugging Face experiments and projects.

Basically the idea is to be able to show Clapper in a single "embedded" view, to be used in an iframe player (eg. hosted on the future 2.0 version of AiTube.at)

Solution

• Repair the preview in embedded mode (it's on the /embed route, see https://clapper.app/embed)
• I think we can also add a separate /watch route with more features (chat assistant to edit the video on the fly, and group chat), that is something that normal users will appreciate too, I think (ability to share a preview link to a colleague or friends etc)