feat(frontend): add student identification screen as entry point

eme-frontend/lib/main.dart

@@ -1,6 +1,6 @@
 import "package:flutter/material.dart";
 import "theme/ensup_theme.dart";
-import "screens/home_screen.dart";
+import "screens/login_screen.dart";
 
 void main() {
   runApp(const EmeApp());
@@ -15,7 +15,7 @@ class EmeApp extends StatelessWidget {
       title: "EME — Emprunt Matériel ENSUP",
       debugShowCheckedModeBanner: false,
       theme: buildEnsupTheme(),
-      home: const HomeScreen(),
+      home: const LoginScreen(),
     );
   }
 }