fix(quotas): unifier le décompte IA (BYOK, rollback) et combler les fuites

Centralise la réserve via ai-quota, corrige admin unavailable (-1), brancher les routes sans quota et le host-pays brainstorm, avec usage-meter élargi, noms de clusters, MCP et ajustements dashboard/insights.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/components/dashboard-agent-carousel.tsx

@@ -76,9 +76,11 @@ export function DashboardAgentCarousel({
       />
 
       {suggestions.length === 0 ? (
-        <p className="text-[11px] text-concrete italic leading-relaxed py-2">
-          {t('homeDashboard.agentsEmpty')}
-        </p>
+        <div className="rounded-xl border border-dashed border-border/35 bg-stone-50/50 dark:bg-zinc-950/30 p-3">
+          <p className="text-[11px] text-concrete leading-relaxed">
+            {t('homeDashboard.agentsEmpty')}
+          </p>
+        </div>
       ) : (
         <AgentSlide
           current={suggestions[idx]}