fix: tema claro blanco, logo 4Ventures y menú original

Fondo blanco en la app; menú con labels/iconos originales; logo en sidebar y login.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/layout.tsx

@@ -27,8 +27,8 @@ export default function RootLayout({
   children: React.ReactNode;
 }) {
   return (
-    <html lang="es" className={`dark ${sans.variable}`}>
-      <body className={`${sans.className} bg-background text-gray-100 min-h-screen antialiased`}>
+    <html lang="es" className={sans.variable}>
+      <body className={`${sans.className} bg-background text-gray-900 min-h-screen antialiased`}>
         {children}
       </body>
     </html>