refactor: production-essentials hardening pass

Backend: structured logger, env-validated config, graceful SIGTERM/SIGINT
shutdown, per-IP rate limiter, per-tier scheduler concurrency latch, error
context on previously-silent catches, compiled-JS Dockerfile stage.

Frontend: lib/api.ts consolidates BACKEND_URL with lazy production-required
check, root + per-segment error.tsx / not-found.tsx / loading.tsx,
generateMetadata on park and ride pages, graceful fallback when backend is
unreachable, Plausible script gated on env vars.

Infra: CI runs lint + typecheck + tests on both packages before docker build,
compose adds healthchecks, log rotation, and memory limits; .env.example
documents every variable.

Cleanup: removed empty app/api/parks/ dir and 0-byte root parks.db, moved
wait-times-urls.txt into docs/, dropped an `as any` cast.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/park/[id]/page.tsx

@@ -1,3 +1,4 @@
+import type { Metadata } from "next";
 import { BackToCalendarLink } from "@/components/BackToCalendarLink";
 import { notFound } from "next/navigation";
 import { PARK_MAP } from "@/lib/parks";
@@ -6,14 +7,45 @@ import { LiveRidePanel } from "@/components/LiveRidePanel";
 import type { RideStatus, RidesFetchResult } from "@/lib/scrapers/sixflags";
 import type { LiveRidesResult } from "@/lib/scrapers/queuetimes";
 import { getTodayLocal } from "@/lib/env";
-
-const BACKEND_URL = process.env.BACKEND_URL ?? "http://localhost:3001";
+import { apiFetch } from "@/lib/api";
+import type { DayData } from "@/lib/types";
 
 interface PageProps {
   params: Promise<{ id: string }>;
   searchParams: Promise<{ month?: string }>;
 }
 
+interface CalendarMonthResponse {
+  parkId: string;
+  year: number;
+  month: number;
+  monthData: Record<string, DayData>;
+  today: string;
+}
+
+interface RidesResponse {
+  parkId: string;
+  today: string;
+  parkOpenToday: boolean;
+  withinWindow: boolean;
+  isWeatherDelay: boolean;
+  liveRides: LiveRidesResult | null;
+  scheduleFallback: RidesFetchResult | null;
+}
+
+export async function generateMetadata({ params }: PageProps): Promise<Metadata> {
+  const { id } = await params;
+  const park = PARK_MAP.get(id);
+  if (!park) return { title: "Park not found | Thoosie Calendar" };
+  const title = `${park.name} | Thoosie Calendar`;
+  const description = `Operating hours and live ride status for ${park.name} (${park.location.city}, ${park.location.state}).`;
+  return {
+    title,
+    description,
+    openGraph: { title, description },
+  };
+}
+
 function parseMonthParam(param: string | undefined): string {
   if (param && /^\d{4}-\d{2}$/.test(param)) {
     const [y, m] = param.split("-").map(Number);
@@ -35,26 +67,25 @@ export default async function ParkPage({ params, searchParams }: PageProps) {
   const [year, month] = monthStr.split("-").map(Number);
 
   const [calendarData, ridesData] = await Promise.all([
-    fetch(`${BACKEND_URL}/api/calendar/${id}/month?month=${monthStr}`, {
-      next: { revalidate: 300 },
-    }).then((r) => r.json()),
-    fetch(`${BACKEND_URL}/api/parks/${id}/rides`, {
-      next: { revalidate: 60 },
-    }).then((r) => r.json()),
+    apiFetch<CalendarMonthResponse>(
+      `/api/calendar/${id}/month?month=${monthStr}`,
+      { revalidate: 300 },
+    ),
+    apiFetch<RidesResponse>(
+      `/api/parks/${id}/rides`,
+      { revalidate: 60 },
+    ),
   ]);
 
+  if (!calendarData) {
+    return <DataUnavailable parkName={park.name} />;
+  }
+
   const { monthData, today } = calendarData;
-  const {
-    parkOpenToday,
-    isWeatherDelay,
-    liveRides,
-    scheduleFallback: ridesResult,
-  }: {
-    parkOpenToday: boolean;
-    isWeatherDelay: boolean;
-    liveRides: LiveRidesResult | null;
-    scheduleFallback: RidesFetchResult | null;
-  } = ridesData;
+  const parkOpenToday = ridesData?.parkOpenToday ?? false;
+  const isWeatherDelay = ridesData?.isWeatherDelay ?? false;
+  const liveRides = ridesData?.liveRides ?? null;
+  const ridesResult = ridesData?.scheduleFallback ?? null;
 
   return (
     <div style={{ minHeight: "100vh", background: "var(--color-bg)" }}>
@@ -355,3 +386,18 @@ function Callout({ children }: { children: React.ReactNode }) {
     </div>
   );
 }
+
+function DataUnavailable({ parkName }: { parkName: string }) {
+  return (
+    <main style={{ minHeight: "100vh", display: "grid", placeItems: "center", padding: 24, background: "var(--color-bg)" }}>
+      <div style={{ maxWidth: 480, textAlign: "center" }}>
+        <h1 style={{ fontSize: "1.2rem", fontWeight: 700, color: "var(--color-text)", marginBottom: 12 }}>
+          {parkName} data is unavailable
+        </h1>
+        <p style={{ color: "var(--color-text-muted)", lineHeight: 1.6, fontSize: "0.9rem" }}>
+          We could not reach the backend. Refresh in a moment.
+        </p>
+      </div>
+    </main>
+  );
+}