feat(admin): Server Action'larla kullanıcı yönetimi ve gerçek oturumlu sayfalar

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/layout/app-shell-fallback.tsx

@@ -0,0 +1,26 @@
+import { Skeleton } from "@/components/ui/skeleton";
+import { tr } from "@/i18n/tr";
+
+/** Oturum okunurken gösterilen kabuk iskeleti (yan menü + üst bar + içerik). */
+export function AppShellFallback() {
+  return (
+    <div role="status" aria-label={tr.common.loading} className="flex min-h-dvh w-full">
+      <div className="hidden w-64 shrink-0 flex-col gap-3 border-r bg-sidebar p-3 md:flex">
+        <Skeleton className="h-8 w-28" />
+        {Array.from({ length: 8 }, (_, i) => (
+          <Skeleton key={i} className="h-7 w-full" />
+        ))}
+      </div>
+      <div className="flex flex-1 flex-col">
+        <div className="flex h-14 items-center gap-2 border-b px-4">
+          <Skeleton className="h-8 w-48" />
+          <Skeleton className="ml-auto size-8 rounded-full" />
+        </div>
+        <div className="flex flex-col gap-4 p-4 md:p-6">
+          <Skeleton className="h-8 w-56" />
+          <Skeleton className="h-24 w-full" />
+        </div>
+      </div>
+    </div>
+  );
+}