Add Tax Management module, Print Labels activity tracking & real-time data

• Add Tax Management page with WooCommerce tax rates (CRUD, toggle, Tax On, Tax Class)
• Add Indirect Tax management with ManageMore POS integration (type names, calc method labels)
• Print Labels: activity tracking (add/remove/print/clear logging)
• Print Labels: real-time UPC/barcode and price fetching from WooCommerce
• Print Labels: bulk variant add with loader, search improvements
• Print Labels: revised print confirmation flow with keep list option
• Admin layout: add Tax Management to sidebar navigation

Co-authored-by: Cursor cursoragent@cursor.com