Enforce filter-specific sorting rules for filter options

When a user views the list of options for filtering by size, the sort appears to be random:


For some options like shoe size, we can get away with filtering the options numerically. However, t-shirt size has a bespoke sort that all users expect: XS > SM > MD > LG > XL . The CMS should have this capability, and all filters for our final product set should be sorted in a way that users expect. This could possibly be an admin capability if it isn't already?

No files, tests, or entry points are named. Start by locating the filter-option list and the CMS configuration for filter values, then verify the expected ordering for numeric sizes and XS > SM > MD > LG > XL; done means every final-product filter displays a predictable, user-expected order.

Written by the indexing model from the issue text.