[codex] Improve desktop startup shell loading (#241)

desktop/src/shared/ui/ViewLoadingFallback.tsx

@@ -0,0 +1,11 @@
+type ViewLoadingFallbackProps = {
+  label: string;
+};
+
+export function ViewLoadingFallback({ label }: ViewLoadingFallbackProps) {
+  return (
+    <div className="flex min-h-0 flex-1 items-center justify-center px-6 py-8">
+      <p className="text-sm text-muted-foreground">{label}</p>
+    </div>
+  );
+}