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/page.tsx

@@ -1,8 +1,10 @@
+import type { ComponentProps } from "react";
 import { cookies } from "next/headers";
 import { HomePageClient } from "@/components/HomePageClient";
 import { getTodayLocal, formatDateLocal } from "@/lib/env";
+import { apiFetch } from "@/lib/api";
 
-const BACKEND_URL = process.env.BACKEND_URL ?? "http://localhost:3001";
+type WeekData = ComponentProps<typeof HomePageClient>;
 
 const WEEK_COOKIE = "tcWeek";
 
@@ -24,10 +26,25 @@ export default async function HomePage() {
   const saved = (await cookies()).get(WEEK_COOKIE)?.value;
   const weekStart = getWeekStart(saved);
 
-  const data = await fetch(
-    `${BACKEND_URL}/api/calendar/week?start=${weekStart}`,
-    { next: { revalidate: 120 } },
-  ).then((r) => r.json());
+  const data = await apiFetch<WeekData>(
+    `/api/calendar/week?start=${weekStart}`,
+    { revalidate: 120 },
+  );
+
+  if (!data) {
+    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 }}>
+            Calendar 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>
+    );
+  }
 
   return <HomePageClient {...data} />;
 }