Delete stale diagnostics and cart placeholder#248

Closes #215

Summary

• delete storefront /audit and /test routes
• delete the Admin sandbox route and regenerate its route tree
• remove the scaffold cart.hello router
• remove the stale /test sitemap exclusion found during review
• retain /benchmark and all benchmark support

Static proof

• apps/storev2: astro check passes with 0 errors; production build completes
• deleted route/router files are absent and cart.hello has no remaining references
• benchmark page, component, Product procedures/query, and benchmark implementation are unchanged from the issue base
• git diff --check passes

External proof blockers

• homepage/products intermittently encounter a local service-binding Network connection lost condition
• normal Google login reaches pending administrator approval, so signed-in dashboard proof needs maintainer action

Draft remains open pending real-boundary proof.