feat: set default color scheme to dark

src/App.tsx

@@ -7,7 +7,7 @@ import { MantineProvider } from '@mantine/core';
 import AppRoutes from './AppRoutes';
 
 export function App() {
-  return <MantineProvider>
+  return <MantineProvider defaultColorScheme='dark'>
     <Notifications />
     <AppRoutes />
   </MantineProvider>;