Add dark mode support and theme provider

src/App.tsx

@@ -12,7 +12,7 @@ import { NuevoIngreso } from '@/sections/NuevoIngreso';
 import { EditIngreso } from '@/sections/EditIngreso';
 import { Spinner } from '@/components/ui/spinner';
 import { Button } from '@/components/ui/button';
-import { ThemeProvider } from '@/contexts/ThemeContext';
+import { ThemeProvider } from "@/components/theme-provider";
 import { Toaster } from '@/components/ui/sonner';
 
 function AppContent() {
@@ -185,7 +185,7 @@ function AppContent() {
             getAreaName={(areaId) => store.areas.find(a => a.id === areaId)?.nombre || ''}
           />
         );
-      
+
       case 'editaringreso': {
         const internacion = store.getInternacionById(store.currentInternacionId || '');
         const paciente = internacion ? store.getPacienteById(internacion.pacienteId) : undefined;
@@ -225,8 +225,7 @@ function AppContent() {
 
 function App() {
   return (
-    // @ts-expect-error - next-themes types mismatch
-    <ThemeProvider attribute="class" defaultTheme="system" enableSystem>
+    <ThemeProvider defaultTheme="dark" storageKey="vite-ui-theme">
       <AppContent />
       <Toaster position="top-right" />
     </ThemeProvider>