feat(#73): Adaptive Weekend shell and responsive navigation

Implemented by claude via .agents/dev dispatch.

frontend/src/pages/WeekendPage.tsx

@@ -0,0 +1,42 @@
+import { useWeekendContext } from '../hooks/useWeekendContext'
+import { BetweenRacesView } from '../components/weekend/BetweenRacesView'
+import { BetweenSessionsView } from '../components/weekend/BetweenSessionsView'
+import { LiveHandoffView } from '../components/weekend/LiveHandoffView'
+import { PreSessionView } from '../components/weekend/PreSessionView'
+import { WeekendError, WeekendLimited, WeekendLoading } from '../components/weekend/StatusViews'
+import type { WeekendContext } from '../types'
+import '../styles/weekend.css'
+
+function renderState(context: WeekendContext, now: Date) {
+  switch (context.state) {
+    case 'loading':
+      return <WeekendLoading />
+    case 'error':
+      return <WeekendError message={context.message} />
+    case 'limited_data':
+      return <WeekendLimited message={context.message} season={context.season} />
+    case 'between_races':
+    case 'post_weekend':
+    case 'season_complete':
+      return <BetweenRacesView context={context} now={now} />
+    case 'between_sessions':
+    case 'session_settling':
+      return <BetweenSessionsView context={context} now={now} />
+    case 'session_live':
+      return <LiveHandoffView context={context} />
+    case 'pre_session':
+      return <PreSessionView context={context} now={now} />
+    default:
+      return <WeekendLimited season={context.season} />
+  }
+}
+
+export function WeekendPage() {
+  const { context, now } = useWeekendContext()
+
+  return (
+    <main className="wk-page" data-testid="weekend-page" data-state={context.state}>
+      {renderState(context, now)}
+    </main>
+  )
+}