Public schedule display settings are clearer and easier to save

Public schedule display settings are now organized into instructor names, spot
counts and urgency, and the optional fuller-appearance controls. Instead of
typing technical values, staff choose plain-language options such as **Places
remaining** or **Percentage booked**, with the matching unit, explanation, and
validation shown beside the threshold.

A live example shows how the current choices will appear to clients. Effective
defaults are shown when a venue has not customized a value yet, dependent
controls are only editable when they apply, and all changes in the section are
saved with one clear action and confirmation.