[SDK Review] Prevent users to add new domains 48 hours or less before the event

_Requested by the SDK Archboard and PMs_

It was brought to attention that we should prevent users to add domains at least 48 hours before the review.

Another idea that was brought up was to tell the users to specify the domains when creating the meeting, and don't allow them to remove them or add new ones when updating the event. In case they don't have the APIview link yet, they can leave it blank and just add it later.

This is related to the quorum concerns. Adding a new domain just before the review could mean that there will not be a quorum for the meeting.

The issue names no files, tests, or entry points; start by locating the event creation and update paths that manage domains. Clarify whether the 48-hour rule applies to additions only or also removals, and whether domains must be supplied at creation. Done means the agreed policy is enforced and its user-facing behavior is covered by tests.

Written by the indexing model from the issue text.