Root cause: app/page.tsx owned `/` and imported the landing component
directly, so `/` only got the root layout. The (landing)/layout.tsx
that supplies .landing-root, the IBM Plex Mono / Libre Baskerville
fonts, and landing.css never ran, so the redesigned page (which is
scoped under .landing-root) rendered with no styles at all. The old
landing used global Tailwind tokens so the missing layout went
unnoticed.
Fix: the canonical App Router structure. `/` now resolves to
app/(landing)/page.tsx (route groups add no path segment), wrapped by
app/(landing)/layout.tsx. The logged-in -> /dashboard redirect moved
into that page. Deleted the duplicate app/page.tsx.
Build clean, no parallel-route conflict, `/` resolves. 266/266 tests
pass.