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

Implemented by claude via .agents/dev dispatch.

frontend/src/components/weekend/PreSessionView.tsx

@@ -0,0 +1,49 @@
+import { Link } from '@tanstack/react-router'
+import { ChevronRight } from 'lucide-react'
+import type { WeekendContext } from '../../types'
+import { RacePreviewPage } from '../../pages/RacePreviewPage'
+import { CountdownDisplay, Flag, SeasonNavStrip, SessionTimeline } from './shared'
+
+/**
+ * PreSessionView folds the race preview surface into the Weekend home so there is
+ * no separate Preview destination. It reuses the existing preview page content and
+ * frames it with the next-session countdown and compact season navigation.
+ */
+export function PreSessionView({ context, now }: { context: WeekendContext; now: Date }) {
+  const next = context.next_event
+  const nextStart = context.next_session?.date_start ?? next?.next_session_start ?? next?.date_start
+
+  return (
+    <div className="wk-pre" data-testid="weekend-pre-session" data-state={context.state}>
+      <div className="wk-eyebrow mono" data-testid="wk-eyebrow">Pre-session</div>
+
+      {next && (
+        <header className="wk-pre-head" data-testid="wk-pre-head">
+          <div className="wk-event-id">
+            <Flag code={next.country_code} flag={next.country_flag} />
+            <h1 className="wk-sessions-title">{next.meeting_name}</h1>
+          </div>
+          <div className="wk-pre-countdown">
+            <span className="wk-next-label mono">
+              {context.next_session?.session_name ?? next.next_session_name ?? 'Next session'}
+            </span>
+            <CountdownDisplay target={nextStart} now={now} />
+          </div>
+          <Link to="/live" className="wk-cta wk-cta-ghost" data-testid="wk-pre-live">
+            Live timing <ChevronRight size={14} aria-hidden="true" />
+          </Link>
+        </header>
+      )}
+
+      {context.sessions && context.sessions.length > 0 && <SessionTimeline sessions={context.sessions} />}
+
+      <div className="wk-pre-preview" data-testid="wk-pre-preview">
+        <RacePreviewPage />
+      </div>
+
+      {context.season_rounds && context.season_rounds.length > 0 && (
+        <SeasonNavStrip rounds={context.season_rounds} />
+      )}
+    </div>
+  )
+}