feat: ajout d'un sélecteur de thèmes avec trois options (P'titsPas, Pastel, Sombre)

frontend/lib/screens/home/home_screen.dart

@@ -1,16 +1,53 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import '../../theme/theme_provider.dart';
+import '../../theme/app_theme.dart';
 
 class HomeScreen extends StatelessWidget {
   const HomeScreen({super.key});
 
+  String _getThemeName(ThemeType type) {
+    switch (type) {
+      case ThemeType.defaultTheme:
+        return "P'titsPas";
+      case ThemeType.pastelTheme:
+        return "Pastel";
+      case ThemeType.darkTheme:
+        return "Sombre";
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: const Text('P\'titsPas'),
+        title: const Text('Accueil'),
+        actions: [
+          Consumer<ThemeProvider>(
+            builder: (context, themeProvider, child) {
+              return Padding(
+                padding: const EdgeInsets.symmetric(horizontal: 16.0),
+                child: DropdownButton<ThemeType>(
+                  value: themeProvider.currentTheme,
+                  items: ThemeType.values.map((ThemeType type) {
+                    return DropdownMenuItem<ThemeType>(
+                      value: type,
+                      child: Text(_getThemeName(type)),
+                    );
+                  }).toList(),
+                  onChanged: (ThemeType? newValue) {
+                    if (newValue != null) {
+                      themeProvider.setTheme(newValue);
+                    }
+                  },
+                ),
+              );
+            },
+          ),
+        ],
       ),
       body: const Center(
-        child: Text('Bienvenue sur P\'titsPas'),
+        child: Text('Bienvenue sur P\'titsPas !'),
       ),
     );
   }