Since Zulip never caught on and we are now using Discourse/Discord, we could shut it down and remove its mentions from the Devguide and elsewhere.

Before pulling the plug, we should:

• check if any stream is still active (none of the ones I followed are), and announce the shutdown;
• check what other pages (e.g. the Devguide) point to Zulip so that they can be updated/removed;
• review if there is any significant thread that we might want to preserve/export.