feat(frontend): add article management tab in moderation page (#72)

Add ArticleManagementTab component with CRUD, filters, pagination,
image upload (500Ko/512px), fix users group SVG icon, and rename
article types dropdown to French.

Author: pierrick-fonquerne

src/frontend/src/components/admin/AdminDashboardStats.tsx

@@ -49,8 +49,8 @@ export function AdminDashboardStats({ stats, isLoading }: AdminDashboardStatsPro
     <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
       <StatCard
         icon={
-          <svg className="w-5 h-5 text-gold-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 4.354a4 4 0 110 5.292M15 21H3v-1a6 6 0 0112 0v1zm0 0h6v-1a6 6 0 00-9-5.197m13.5-9a2.5 2.5 0 11-5 0 2.5 2.5 0 015 0z" />
+          <svg className="w-5 h-5 text-gold-400" fill="none" stroke="currentColor" strokeWidth={1.5} viewBox="0 0 24 24">
+            <path strokeLinecap="round" strokeLinejoin="round" d="M15 19.128a9.38 9.38 0 0 0 2.625.372 9.337 9.337 0 0 0 4.121-.952 4.125 4.125 0 0 0-7.533-2.493M15 19.128v-.003c0-1.113-.285-2.16-.786-3.07M15 19.128v.106A12.318 12.318 0 0 1 8.624 21c-2.331 0-4.512-.645-6.374-1.766l-.001-.109a6.375 6.375 0 0 1 11.964-3.07M12 6.375a3.375 3.375 0 1 1-6.75 0 3.375 3.375 0 0 1 6.75 0Zm8.25 2.25a2.625 2.625 0 1 1-5.25 0 2.625 2.625 0 0 1 5.25 0Z" />
           </svg>
         }
         label="Utilisateurs"