Clearweb integrations for important apps

[ajlamarc]

To make pitching Realm to DAOs and other organizations easier, some of its apps will need to need to be accessible to outsiders via invite URL without them having a full ship.

• Engram: share view / edit links like you would in Google Docs. Free users can edit existing docs (changes go to the host ship) but cannot create their own.
• Calendar: view / edit a shared calendar. Free users cannot create their own calendar.
• Chat: Can join chats but not host them. (Two free users cannot DM each other). Implementation is similar to current chat: client stores current diff index so it knows what updates to request for.
• Rooms / Multiplayer / Campfire: Free users can be in a voice / video call, and watch via screenshare a multiplayer session. They cannot control a cursor, however.

These integrations tie nicely with libames: browser/mobile communicates to a separate host ship without a source ship.