fix(auth): connexion admin - token snake_case, routes GoRouter, profil (Closes #84)

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/services/auth_service.dart

@@ -23,13 +23,15 @@ class AuthService {
 
       if (response.statusCode == 200 || response.statusCode == 201) {
         final data = jsonDecode(response.body);
-        
-        // Stocker les tokens
-        await TokenService.saveToken(data['accessToken']);
-        await TokenService.saveRefreshToken(data['refreshToken']);
-        
-        // Récupérer le profil utilisateur pour avoir toutes les infos
-        final user = await _fetchUserProfile(data['accessToken']);
+        // API renvoie access_token / refresh_token (snake_case)
+        final accessToken = data['access_token'] as String? ?? data['accessToken'] as String?;
+        final refreshToken = data['refresh_token'] as String? ?? data['refreshToken'] as String?;
+        if (accessToken == null) throw Exception('Token absent dans la réponse serveur');
+
+        await TokenService.saveToken(accessToken);
+        await TokenService.saveRefreshToken(refreshToken ?? '');
+
+        final user = await _fetchUserProfile(accessToken);
         
         // Stocker l'utilisateur en cache
         await _saveCurrentUser(user);
@@ -80,8 +82,9 @@ class AuthService {
         Uri.parse('${ApiConfig.baseUrl}${ApiConfig.changePasswordRequired}'),
         headers: ApiConfig.authHeaders(token),
         body: jsonEncode({
-          'currentPassword': currentPassword,
-          'newPassword': newPassword,
+          'mot_de_passe_actuel': currentPassword,
+          'nouveau_mot_de_passe': newPassword,
+          'confirmation_mot_de_passe': newPassword,
         }),
       );