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/globals.css

@@ -679,3 +679,164 @@ td {
   margin: 0 0 0.7rem;
   font-size: 1.15rem;
 }
+
+/* ── Public design system (faithful to the atom theme) ──────────
+   content-card = surface card with a primary-tinted header (icon +
+   title + subtitle) and a padded body — the signature atom block. */
+.content-card {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  background: var(--color-surface);
+  color: var(--color-text);
+  border: 1px solid color-mix(in srgb, var(--color-text-muted) 15%, transparent);
+  border-radius: 14px;
+  box-shadow: var(--shadow-card);
+  overflow: hidden;
+}
+.content-card-head {
+  display: flex;
+  align-items: center;
+  gap: 0.7rem;
+  padding: 0.85rem 1rem;
+  background: color-mix(in srgb, var(--color-primary) 9%, var(--color-surface));
+  border-bottom: 1px solid color-mix(in srgb, var(--color-text-muted) 10%, transparent);
+}
+.content-card-icon {
+  flex: none;
+  width: 44px;
+  height: 44px;
+  border-radius: 999px;
+  display: grid;
+  place-items: center;
+  font-size: 1.25rem;
+  background: color-mix(in srgb, var(--color-primary) 18%, var(--color-surface));
+  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--color-primary) 30%, transparent);
+}
+.content-card-head-text {
+  min-width: 0;
+  flex: 1;
+}
+.content-card-title {
+  margin: 0;
+  font-weight: 700;
+  font-size: 1rem;
+  line-height: 1.2;
+}
+.content-card-subtitle {
+  margin: 0.15rem 0 0;
+  font-size: 0.78rem;
+  color: var(--color-text-muted);
+}
+.content-card-action {
+  flex: none;
+}
+.content-card-body {
+  padding: 1rem;
+}
+
+/* Responsive card grids (atom: 1 / sm2 / md3 / lg4). */
+.card-grid {
+  display: grid;
+  gap: 1rem;
+  grid-template-columns: 1fr;
+}
+@media (min-width: 40rem) {
+  .card-grid.sm-2 { grid-template-columns: repeat(2, 1fr); }
+}
+@media (min-width: 48rem) {
+  .card-grid.md-2 { grid-template-columns: repeat(2, 1fr); }
+  .card-grid.md-3 { grid-template-columns: repeat(3, 1fr); }
+}
+@media (min-width: 64rem) {
+  .card-grid.lg-3 { grid-template-columns: repeat(3, 1fr); }
+  .card-grid.lg-4 { grid-template-columns: repeat(4, 1fr); }
+}
+
+/* Stat tiles (value in the primary colour + muted label). */
+.stat-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
+  gap: 0.85rem;
+}
+.stat-block {
+  background: var(--color-background);
+  border: 1px solid color-mix(in srgb, var(--color-text-muted) 12%, transparent);
+  border-radius: 12px;
+  padding: 0.85rem 1rem;
+  text-align: center;
+}
+.stat-block-value {
+  font-size: 1.6rem;
+  font-weight: 800;
+  line-height: 1.1;
+  color: var(--color-primary);
+}
+.stat-block-label {
+  margin-top: 0.2rem;
+  font-size: 0.78rem;
+  color: var(--color-text-muted);
+}
+
+/* Empty states */
+.empty-state {
+  text-align: center;
+  padding: 2rem 1rem;
+}
+.empty-state-icon {
+  font-size: 2rem;
+  margin-bottom: 0.4rem;
+}
+
+/* Online / offline pill */
+.online-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.35rem;
+  font-size: 0.74rem;
+  font-weight: 700;
+  padding: 0.1rem 0.55rem 0.1rem 0.45rem;
+  border-radius: 999px;
+  background: color-mix(in srgb, var(--color-text-muted) 14%, transparent);
+  color: var(--color-text-muted);
+}
+.online-badge.online {
+  background: color-mix(in srgb, #16a34a 16%, transparent);
+  color: #15803d;
+}
+.online-dot {
+  width: 8px;
+  height: 8px;
+  border-radius: 999px;
+  background: currentColor;
+}
+.online-badge.online .online-dot {
+  background: #16a34a;
+  box-shadow: 0 0 0 3px color-mix(in srgb, #16a34a 22%, transparent);
+}
+
+/* Leaderboard rank chip */
+.rank-badge {
+  display: inline-grid;
+  place-items: center;
+  min-width: 2.1rem;
+  height: 2.1rem;
+  padding: 0 0.35rem;
+  border-radius: 999px;
+  font-weight: 800;
+  font-size: 0.95rem;
+  background: var(--color-background);
+  border: 1px solid color-mix(in srgb, var(--color-text-muted) 18%, transparent);
+}
+.rank-badge.rank-1 {
+  background: color-mix(in srgb, #eab308 20%, transparent);
+  border-color: #eab308;
+}
+.rank-badge.rank-2 {
+  background: color-mix(in srgb, #94a3b8 22%, transparent);
+  border-color: #94a3b8;
+}
+.rank-badge.rank-3 {
+  background: color-mix(in srgb, #f97316 20%, transparent);
+  border-color: #f97316;
+}