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/rares/[category]/page.tsx

@@ -1,3 +1,4 @@
+import { getTranslations } from "next-intl/server";
 import Link from "next/link";
 import { notFound } from "next/navigation";
 import { ContentCard, EmptyState } from "@/components/public/ui";
@@ -16,17 +17,19 @@ type RareRow = {
   itemId: number | null;
 };
 
-function prettyCurrency(type: string): string {
+type CurrencyTranslator = (key: string) => string;
+
+function prettyCurrency(type: string, t: CurrencyTranslator): string {
   switch (type) {
     case "0":
     case "duckets":
-      return "Duckets";
+      return t("duckets");
     case "5":
     case "diamonds":
-      return "Diamonds";
+      return t("diamonds");
     case "-1":
     case "credits":
-      return "Credits";
+      return t("credits");
     default:
       return type.charAt(0).toUpperCase() + type.slice(1);
   }
@@ -37,6 +40,7 @@ export default async function RareCategoryPage({
 }: {
   params: Promise<{ category: string }>;
 }) {
+  const t = await getTranslations("pages.rareCategory");
   const { category } = await params;
 
   let categoryId: bigint;
@@ -98,25 +102,25 @@ export default async function RareCategoryPage({
             {cat.name}
           </span>
         }
-        subtitle={`${rares.length} ${rares.length === 1 ? "rare" : "rares"} in this category`}
+        subtitle={t("rareCount", { count: rares.length })}
         action={
           <Link className="btn btn-outline" href="/rares">
-            ← All rares
+            {t("allRares")}
           </Link>
         }
         padded={rares.length === 0}
       >
         {rares.length === 0 ? (
-          <EmptyState icon="💎">No rares listed in this category yet.</EmptyState>
+          <EmptyState icon="💎">{t("empty")}</EmptyState>
         ) : (
           <div style={{ padding: "0.25rem 1rem 0.75rem", overflowX: "auto" }}>
             <table>
               <thead>
                 <tr>
                   <th style={{ width: 56 }}></th>
-                  <th>Rare</th>
-                  <th>Credits</th>
-                  <th>Currency</th>
+                  <th>{t("colRare")}</th>
+                  <th>{t("colCredits")}</th>
+                  <th>{t("colCurrency")}</th>
                 </tr>
               </thead>
               <tbody>
@@ -147,14 +151,14 @@ export default async function RareCategoryPage({
                       </td>
                       <td>
                         {r.creditValue && r.creditValue !== "" ? (
-                          `${r.creditValue} credits`
+                          t("creditsValue", { value: r.creditValue })
                         ) : (
                           <span className="muted">—</span>
                         )}
                       </td>
                       <td>
                         {r.currencyValue && r.currencyValue !== "" ? (
-                          `${r.currencyValue} ${prettyCurrency(r.currencyType)}`
+                          `${r.currencyValue} ${prettyCurrency(r.currencyType, t)}`
                         ) : (
                           <span className="muted">—</span>
                         )}