Ship crab.fit in the webxdc container format for tight messenger integration

[missytake]

Proposed feature or solution

The webxdc container format allows to run a web app inside a chat, without a server. It removes any need for hosting a database, showing a cookie banner, user management, and prevents tracking by sandboxing the web app from the Internet. webxdc is an open standard supported by Delta Chat and Cheogram so far.

crab.fit offers pretty much the best scheduling UX out there. Being integrated tightly into a messenger would improve on that; users don't need to open a browser to enter their preferred dates, there could be notifications when a consensus is emerging, when a deadline is approaching, and warnings could be sent directly to the chat if there is no date where everyone can make it.

Alternatives

The status quo is already pretty neat and works great for most groups. But some features can only be achieved by the tight messenger integration webxdc provides.

Additional information

Porting it shouldn't be hard; basically all calls to a database need to ripped out, so the data gets stored in webxdc updates instead. Getting data needs to be done in a function called by setUpdateListener. And then it needs to be packed into a .zip file so it can be sent around or uploaded to xstore.