fix: landing page rendered unstyled - route bypassed (landing) layout

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.

app/(landing)/page.tsx

@@ -1,4 +1,6 @@
 import Link from 'next/link'
+import { redirect } from 'next/navigation'
+import { createClient } from '@/lib/supabase/server'
 import { BrandMark } from '@/components/brand-mark'
 import { GithubIcon, ArrowIcon } from '@/components/landing/icons'
 import { ResourceShowcase } from '@/components/landing/resource-showcase'
@@ -19,7 +21,14 @@ const STEPS = [
   { num: '03', title: 'Seed your ops docs', desc: 'Drop in SOPs, credentials, and area leads. The whole board has one place to look things up.' },
 ]
 
-export default function LandingPage() {
+export default async function LandingPage() {
+  // `/` resolves here (route group adds no path segment), so this page is
+  // wrapped by (landing)/layout.tsx which supplies the .landing-root theme,
+  // fonts, and landing.css. Logged-in visitors skip the marketing page.
+  const supabase = await createClient()
+  const { data: { user } } = await supabase.auth.getUser()
+  if (user) redirect('/dashboard')
+
   return (
     <>
       <nav className="landing-nav">

app/page.tsx

@@ -1,12 +0,0 @@
-import { createClient } from '@/lib/supabase/server'
-import { redirect } from 'next/navigation'
-import LandingPage from './(landing)/page'
-
-export default async function RootPage() {
-  const supabase = await createClient()
-  const { data: { user } } = await supabase.auth.getUser()
-  if (user) {
-    redirect('/dashboard')
-  }
-  return <LandingPage />
-}