Collaboration via Yjs

[JammingBen]

This is a collection of tasks for bringing collaboration via Yjs to OpenCloud.

Tasks

Groundwork

• Bring feat(yjs): collaborative editing framework #2785 into a mergable state, then review and merge it @JammingBen

Direct follow-ups

These should happen before we officially announce this as productized.

• appVersion is 0.0.0 (private package placeholder), so both version gates are dead code in production
• Container hygiene: floating node:22-alpine (type stripping needs > = 22.18), no HEALTHCHECK, no SIGTERM handler, no depends_on in compose
• Add e2e tests
• Add unit tests for services/realtime
• Publish the hocuspocus Docker image and set up CI for future releases
• Add the published image to the opencloud-compose setup (default?)

Can happen later

• Make "Show source" work for markdown files despite collaboration enabled on the system
• Show avatars of users in the current session (toolbar top right, click opens sharing/members panel?)
• Grab the Excalidraw extension from feat(yjs): collaborative editing framework #2755 and port it to web-extensions
• Add dev docs on how to write an extension using collaboration
• Check compatibility in vaults, i.e. can we make it work in vaults?

Needs to be discussed

• Version handling & auto saving
• Known limits in dev/docs/collaboration.md

[dschmidt]

Check compatibility in vaults, i.e. can we make it work in vaults?

Yes, absolutely - but the question is rather: can we encrypt the Yjs traffic using the vault passphrase so the content is not leaked to the server?
Is that "secure" enough or do a lot of small messages allow easier decryption of the passphrase?