[Scheduling tool] Users should not be able to schedule reviews without 2 business days before the session

Currently users of the scheduling tool can schedule a meeting for a Monday on a Friday. This does not give the architects enough time to review the materials prior to the meeting. The scheduling tool should use only business days for limiting how soon a user can schedule a meeting.

Start by locating the scheduling tool's validation entry point and any tests covering the minimum scheduling window. Reproduce the Friday-to-Monday case and trace how the current limit is calculated. Done means scheduling respects business days and the relevant tests cover the two-business-day requirement.

Written by the indexing model from the issue text.