Adapt + improve all public pages to the atom design system

Extended the same design-system treatment to the public site, faithful
to AtomCMS's "atom" theme. New src/components/public/ui.tsx provides the
signature atom building blocks + a scoped CSS layer:
- ContentCard: surface card with a primary-tinted header (icon circle +
  title + subtitle) and padded body — the atom content-card, used as
  every page's header and section wrapper.
- StatBlock / stat-grid, EmptyState, OnlineBadge (online/offline pill),
  RankBadge (medals for the top 3), and responsive .card-grid helpers.

Swept ~45 public pages (home/community/rankings hand-built as the
reference; the rest via parallel agents that read the schema and
preserved every query, server action, auth gate and field name):
heroes → ContentCard headers, lists → card-grids in ContentCards,
"no X" → EmptyState, status → OnlineBadge/RankBadge. The leaderboard
gained Credits/Diamonds/Duckets tabs (usersCurrency).

Behaviour unchanged. Verified on the prod server against amx_test: 15+
public pages render the content-cards/grids with real data, no errors;
computed styles confirm the tinted header, icon circle, medal + online
pills. Fixed an undefined --color-golden ref. tsc 0, vitest 49/49,
next build 0.

src/app/radio/contests/page.tsx

@@ -1,4 +1,5 @@
 import Link from "next/link";
+import { ContentCard, EmptyState } from "@/components/public/ui";
 import { prisma } from "@/lib/prisma";
 
 export const dynamic = "force-dynamic";
@@ -17,33 +18,39 @@ export default async function RadioContestsPage() {
     .catch(() => []);
 
   return (
-    <main>
-      <div className="hero">
-        <h1 style={{ margin: 0 }}>Radio Contests</h1>
-        <p className="muted" style={{ margin: "0.5rem 0 0" }}>
-          Tune in and take part in our latest on-air contests.
-        </p>
-      </div>
+    <main style={{ display: "grid", gap: "1.5rem" }}>
+      <ContentCard
+        icon="🎉"
+        title="Radio Contests"
+        subtitle="Tune in and take part in our latest on-air contests"
+      />
 
-      {contests.length === 0 ? (
-        <p className="muted">No contests yet.</p>
-      ) : (
-        <div className="grid cols-2">
-          {contests.map((c) => {
-            const id = c.id.toString();
-            return (
-              <article key={id} className="card hover">
-                <h3 style={{ margin: "0 0 0.25rem" }}>
-                  <Link href={`/radio/contests/${id}`}>Contest #{id}</Link>
-                </h3>
-                <p className="muted" style={{ margin: 0 }}>
-                  {formatDate(c.createdAt) || "Date unknown"}
-                </p>
-              </article>
-            );
-          })}
-        </div>
-      )}
+      <ContentCard padded={contests.length === 0}>
+        {contests.length === 0 ? (
+          <EmptyState icon="🎉">No contests yet.</EmptyState>
+        ) : (
+          <div className="card-grid sm-2 lg-3" style={{ padding: "1rem" }}>
+            {contests.map((c) => {
+              const id = c.id.toString();
+              return (
+                <Link
+                  key={id}
+                  href={`/radio/contests/${id}`}
+                  className="card hover"
+                  style={{ color: "inherit", textDecoration: "none", display: "grid", gap: "0.3rem" }}
+                >
+                  <h3 style={{ margin: 0, fontSize: "1rem" }}>
+                    <span aria-hidden>🎉</span> Contest #{id}
+                  </h3>
+                  <p className="muted" style={{ margin: 0 }}>
+                    {formatDate(c.createdAt) || "Date unknown"}
+                  </p>
+                </Link>
+              );
+            })}
+          </div>
+        )}
+      </ContentCard>
     </main>
   );
 }