i18n: translate all public page bodies (EN + IT)

Internationalised the ~44 public pages with next-intl (the shell was
already translated). Each page now pulls its copy from a "pages.<slug>"
namespace via getTranslations (server) / useTranslations (client); the
EN + IT catalogs were authored by parallel agents and merged centrally,
with natural Italian (ICU plurals) and it backfilled from en for any
gap. request.ts gained getMessageFallback/onError so a missing key
degrades to the English value, never a raw key.

Behaviour unchanged (only display text moved to t() calls; queries,
actions, fields, ContentCard structure preserved). Verified on the prod
server: with NEXT_LOCALE=it, home/community/staff/news/shop/rankings all
render Italian copy, no raw-key leakage; English unchanged. The nav
language switcher toggles EN/IT live. tsc 0, vitest 49/49, next build 0.

Admin pages intentionally left in English (staff tooling).

src/app/maintenance/page.tsx

@@ -1,9 +1,11 @@
+import { getTranslations } from "next-intl/server";
 import { ContentCard } from "@/components/public/ui";
 import { siteSettings } from "@/lib/services/site-settings";
 
 export const dynamic = "force-dynamic";
 
 export default async function MaintenancePage() {
+  const t = await getTranslations("pages.maintenance");
   const [hotel, message] = await Promise.all([
     siteSettings.get("hotel_name", "Atom"),
     siteSettings.get(
@@ -16,12 +18,12 @@ export default async function MaintenancePage() {
     <main style={{ maxWidth: 560, margin: "2rem auto" }}>
       <ContentCard
         icon="🛠️"
-        title={`${hotel} is under maintenance`}
-        subtitle="We'll be back shortly"
+        title={t("title", { hotel: hotel ?? "Atom" })}
+        subtitle={t("subtitle")}
       >
         <p style={{ marginTop: 0 }}>{message}</p>
         <p className="muted" style={{ marginBottom: 0 }}>
-          Staff can still log in.
+          {t("staffCanLogIn")}
         </p>
       </ContentCard>
     </main>