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/u/[username]/page.tsx

@@ -1,4 +1,5 @@
 import type { Metadata } from "next";
+import { getTranslations } from "next-intl/server";
 import { notFound } from "next/navigation";
 import { ContentCard, EmptyState, OnlineBadge, StatBlock } from "@/components/public/ui";
 import { auth } from "@/lib/auth";
@@ -39,6 +40,7 @@ export default async function ProfilePage({
 }: {
   params: Promise<{ username: string }>;
 }) {
+  const t = await getTranslations("pages.profile");
   const { username } = await params;
 
   const [user, imagerBase, session] = await Promise.all([
@@ -115,22 +117,22 @@ export default async function ProfilePage({
           <div style={{ minWidth: 0, flex: 1 }}>
             <h1 style={{ margin: "0 0 0.25rem" }}>{user.username}</h1>
             <p style={{ margin: "0 0 0.6rem" }}>
-              {user.motto || <span className="muted">No motto</span>}
+              {user.motto || <span className="muted">{t("noMotto")}</span>}
             </p>
             <OnlineBadge online={user.online === "1"} />
           </div>
         </div>
         <div className="stat-grid" style={{ padding: "0 1.1rem 1.1rem" }}>
-          <StatBlock icon="🏅" value={user.rank} label="Rank" />
-          <StatBlock icon="💰" value={user.credits.toLocaleString()} label="Credits" />
-          <StatBlock icon="📅" value={registered} label="Registered" />
+          <StatBlock icon="🏅" value={user.rank} label={t("statRank")} />
+          <StatBlock icon="💰" value={user.credits.toLocaleString()} label={t("statCredits")} />
+          <StatBlock icon="📅" value={registered} label={t("statRegistered")} />
         </div>
       </ContentCard>
 
       {/* ── Badges ───────────────────────────────────────────── */}
-      <ContentCard icon="🏅" title="Badges" padded={badges.length === 0}>
+      <ContentCard icon="🏅" title={t("badgesTitle")} padded={badges.length === 0}>
         {badges.length === 0 ? (
-          <EmptyState icon="🏅">No badges yet.</EmptyState>
+          <EmptyState icon="🏅">{t("badgesEmpty")}</EmptyState>
         ) : (
           <div
             style={{
@@ -157,9 +159,9 @@ export default async function ProfilePage({
       </ContentCard>
 
       {/* ── Photos ───────────────────────────────────────────── */}
-      <ContentCard icon="📸" title="Photos" padded={photos.length === 0}>
+      <ContentCard icon="📸" title={t("photosTitle")} padded={photos.length === 0}>
         {photos.length === 0 ? (
-          <EmptyState icon="📸">No photos yet.</EmptyState>
+          <EmptyState icon="📸">{t("photosEmpty")}</EmptyState>
         ) : (
           <div className="card-grid sm-2 lg-3" style={{ padding: "1rem" }}>
             {photos.map((p) => (
@@ -180,7 +182,7 @@ export default async function ProfilePage({
       </ContentCard>
 
       {/* ── Guestbook ────────────────────────────────────────── */}
-      <ContentCard icon="📝" title="Guestbook" subtitle={`Messages on ${user.username}'s wall`}>
+      <ContentCard icon="📝" title={t("guestbookTitle")} subtitle={t("guestbookSubtitle", { username: user.username })}>
         {isLoggedIn ? (
           <form action={postGuestbook} className="card" style={{ marginBottom: "1rem" }}>
             {/* Profile owner id drives the write target; the author is taken from
@@ -188,7 +190,7 @@ export default async function ProfilePage({
             <input type="hidden" name="profileId" value={String(user.id)} />
             <input type="hidden" name="username" value={user.username} />
             <label htmlFor="gb-message" className="muted">
-              Leave a message
+              {t("leaveMessage")}
             </label>
             <textarea
               id="gb-message"
@@ -196,19 +198,19 @@ export default async function ProfilePage({
               required
               maxLength={255}
               rows={3}
-              placeholder={`Write something on ${user.username}'s guestbook…`}
+              placeholder={t("guestbookPlaceholder", { username: user.username })}
               style={{ width: "100%", margin: "0.4rem 0 0.75rem", resize: "vertical" }}
             />
             <button type="submit" className="btn btn-primary">
-              Post
+              {t("post")}
             </button>
           </form>
         ) : (
-          <p className="muted">Log in to leave a guestbook message.</p>
+          <p className="muted">{t("loginToPost")}</p>
         )}
 
         {guestbook.length === 0 ? (
-          <EmptyState icon="📝">No guestbook entries yet.</EmptyState>
+          <EmptyState icon="📝">{t("guestbookEmpty")}</EmptyState>
         ) : (
           <div className="grid" style={{ gap: "0.75rem" }}>
             {guestbook.map((g) => {
@@ -234,7 +236,7 @@ export default async function ProfilePage({
                   ) : null}
                   <div style={{ flex: 1 }}>
                     <p style={{ margin: "0 0 0.25rem" }}>
-                      <strong>{author?.username ?? `User #${g.userId}`}</strong>{" "}
+                      <strong>{author?.username ?? t("unknownUser", { id: g.userId })}</strong>{" "}
                       <span className="muted">{formatDate(g.createdAt)}</span>
                     </p>
                     <p style={{ margin: 0 }}>{g.message}</p>