v3.18.37 — Fix: gate slug mismatch

is_dishdash_page() now correctly matches cart-dd, checkout-dd, my-restaurant-account, and reserve-table via get_global_header_slugs(), fixing missing GA4/gtag and all frontend CSS/JS on these pages. Old broken checks (cart, checkout, my-account) kept for white-label compatibility with other installs. Confirmed live: no customer traffic currently reaches /cart-dd/ or /checkout-dd/ directly, so this is a correctness fix rather than a live revenue leak. The separate, pre-existing broken form on /reserve-table/ (zero JS wired to its fields) remains unfixed — tracked for a future release. See RELEASE.md.