Allow customer tags to define memberships (and combos - tags and items in subs)

You can now grant membership benefits to customers based on their Shopify customer tags, not just active subscriptions. Combine a tag filter (any, all, or not) with an existing subscription tier to refine who qualifies, or create a tag-only tier that's checked in real time at checkout — perfect for cohorts like "Founders Club" or "Event Attendee" that you manage through tags. Each membership tier now also gets its own auto-generated Shopify segment so you can see the live member list at a glance.