feat: Puente Mayúscula-Minúscula + TTS SpeechSynthesis + E2E fixes

components/ui/skeleton.tsx

@@ -0,0 +1,15 @@
+import { cn } from "@/lib/utils"
+
+function Skeleton({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) {
+  return (
+    <div
+      className={cn("animate-pulse rounded-md bg-muted", className)}
+      {...props}
+    />
+  )
+}
+
+export { Skeleton }