Cart Route

Single GoRoute pointing /cart at CartScreen, declared inside the ShellRoute so the nav bar stays visible. Not gated by a custom guard — the global auth redirect already blocks guests from logged-in routes.

1. context.go(AppRoute.cart.path) from a home tile or top-bar icon.
2. ShellRoute builder wraps CartScreen with AppShellScaffold.
3. Back behavior delegates to context.pop() which lands on the previous shell route.

• Deep-link to /cart while not logged in → redirect bounces to /login because the auth guard fires before the route builder.
• Adding a per-tab badge for cart count would consume cartControllerProvider in app_shell_scaffold.

• lib/src/core/routing/app_router.dart:378 // /cart route
• lib/src/core/routing/routes.dart // AppRoute.cart

CartScreen is intentionally not a bottom-nav destination — it's reached from home tiles and product details, not from the persistent nav.