feat(frontend): scaffold Flutter Web app with ENSUP home screen

eme-frontend/lib/main.dart

@@ -0,0 +1,21 @@
+import "package:flutter/material.dart";
+import "theme/ensup_theme.dart";
+import "screens/home_screen.dart";
+
+void main() {
+  runApp(const EmeApp());
+}
+
+class EmeApp extends StatelessWidget {
+  const EmeApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: "EME — Emprunt Matériel ENSUP",
+      debugShowCheckedModeBanner: false,
+      theme: buildEnsupTheme(),
+      home: const HomeScreen(),
+    );
+  }
+}