feat: implement shared LoadingModal component and integrate into dashboard route loading states

src/app/(dashboard)/dashboard/loading.tsx

@@ -1,27 +1,5 @@
+import LoadingModal from "@/components/shared/loading-modal";
+
 export default function DashboardLoading() {
-    return (
-        <div className="flex flex-col gap-6 animate-pulse">
-            {/* Header skeleton */}
-            <div className="flex items-center justify-between">
-                <div className="h-7 w-48 rounded-lg bg-[var(--bg-elevated)]" />
-                <div className="h-5 w-32 rounded-lg bg-[var(--bg-elevated)]" />
-            </div>
-
-            {/* KPI cards row */}
-            <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
-                {Array.from({ length: 4 }).map((_, i) => (
-                    <div key={i} className="h-28 rounded-2xl bg-[var(--bg-elevated)] border border-[var(--border)]" />
-                ))}
-            </div>
-
-            {/* Main content area */}
-            <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
-                <div className="h-64 rounded-2xl bg-[var(--bg-elevated)] border border-[var(--border)]" />
-                <div className="h-64 rounded-2xl bg-[var(--bg-elevated)] border border-[var(--border)]" />
-            </div>
-
-            {/* Bottom tables */}
-            <div className="h-80 rounded-2xl bg-[var(--bg-elevated)] border border-[var(--border)]" />
-        </div>
-    );
+    return <LoadingModal message="Chargement des données" subMessage="Récupération du tableau de bord..." />;
 }