use comas in big numbers throughout codebase

modified: models/coupon.py modified: templates/base.j2 modified: templates/cart.j2 modified: templates/cart_checkout.j2 modified: templates/home.j2 modified: templates/product.j2 modified: templates/products.j2 modified: templates/shop.j2 modified: templates/shop_products.j2

Summary by CodeRabbit

• Improvement
  • Enhanced readability of discount and cart qualifier values in the coupon section.
  • Improved the display format for cart total and count, as well as product prices across various sections (cart, shop, and product pages).
  • Updated quantity, price, and rate displays for better clarity and consistency.

This update ensures a more user-friendly and visually appealing experience when viewing prices and totals on the platform.