feat: persistent Coaster Mode toggle in header top-right

- Moves the coaster toggle out of WeekNav and into the homepage header
  top-right as "🎢 Coaster Mode", alongside the parks open badge
- State is stored in localStorage ("coasterMode") so the preference
  persists across sessions and page refreshes
- Dropped the ?coasters=1 URL param entirely; the server always fetches
  both rideCounts and coasterCounts, and HomePageClient picks which to
  display client-side — no flash or server round-trip on toggle
- Individual park pages: LiveRidePanel reads localStorage on mount and
  pre-selects the Coasters Only filter when Coaster Mode is active
- Extracted HomePageClient (client component) to own the full homepage
  UI; page.tsx is now pure data-fetching

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/LiveRidePanel.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState } from "react";
+import { useState, useEffect } from "react";
 import type { LiveRidesResult, LiveRide } from "@/lib/scrapers/queuetimes";
 
 interface LiveRidePanelProps {
@@ -13,6 +13,13 @@ export function LiveRidePanel({ liveRides, parkOpenToday }: LiveRidePanelProps)
   const hasCoasters = rides.some((r) => r.isCoaster);
   const [coastersOnly, setCoastersOnly] = useState(false);
 
+  // Pre-select coaster filter if Coaster Mode is enabled on the homepage.
+  useEffect(() => {
+    if (hasCoasters && localStorage.getItem("coasterMode") === "true") {
+      setCoastersOnly(true);
+    }
+  }, [hasCoasters]);
+
   const visible = coastersOnly ? rides.filter((r) => r.isCoaster) : rides;
   const openRides = visible.filter((r) => r.isOpen);
   const closedRides = visible.filter((r) => !r.isOpen);