Stock header experience: logo + primary navigation + mobile drawer composed in the header shell's slots (Default pure-placeholder shell). Reuses the shared header content items. The composition a partial design places inside header@1's placeholders — the 1:1 replacement for the retired standard-header partial.

• src/components/registry/experiences/partial-designs/header-brand-nav/header-brand-nav.tsx→components/registry/experiences/partial-designs/header-brand-nav/header-brand-nav.tsx
• src/components/registry/experiences/partial-designs/header-brand-nav/header-brand-nav.recipe.ts→src/recipes/header-brand-nav.recipe.ts