feat: Establish initial application structure, theming, responsive utilities, and core feature screens.

lib/core/services/user_api_service.dart

@@ -0,0 +1,148 @@
+import '../api/api_client.dart';
+import '../models/app_user.dart';
+
+/// Service for user management via API (Admin only)
+class UserApiService {
+  final ApiClient _api = ApiClient();
+
+  /// Get all users (Admin only)
+  Future<List<AppUser>> getAllUsers() async {
+    try {
+      _api.restoreToken();
+      final response = await _api.get('/api/users');
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        final usersData = data['users'] as List;
+        return usersData.map((u) => AppUser(
+          id: u['id'] as String,
+          username: u['username'] as String,
+          passwordHash: '',
+          isAdmin: u['isAdmin'] as bool? ?? false,
+          createdAt: DateTime.tryParse(u['createdAt'] ?? '') ?? DateTime.now(),
+        )).toList();
+      }
+      return [];
+    } catch (e) {
+      throw Exception('Failed to fetch users: $e');
+    }
+  }
+
+  /// Create a new user (Admin only)
+  Future<UserResult> createUser({
+    required String username,
+    required String password,
+    bool isAdmin = false,
+  }) async {
+    try {
+      _api.restoreToken();
+      final response = await _api.post('/api/users', data: {
+        'username': username,
+        'password': password,
+        'isAdmin': isAdmin,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        final userData = data['user'] as Map<String, dynamic>;
+        return UserResult(
+          success: true,
+          user: AppUser(
+            id: userData['id'] as String,
+            username: userData['username'] as String,
+            passwordHash: '',
+            isAdmin: userData['isAdmin'] as bool? ?? false,
+            createdAt: DateTime.now(),
+          ),
+        );
+      }
+      return UserResult(
+        success: false,
+        error: data['error'] as String? ?? 'Failed to create user',
+      );
+    } catch (e) {
+      return UserResult(success: false, error: 'Network error: $e');
+    }
+  }
+
+  /// Update user password (Admin only)
+  Future<UserResult> updatePassword({
+    required String userId,
+    required String newPassword,
+  }) async {
+    try {
+      _api.restoreToken();
+      final response = await _api.put('/api/users/$userId/password', data: {
+        'password': newPassword,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        return UserResult(success: true);
+      }
+      return UserResult(
+        success: false,
+        error: data['error'] as String? ?? 'Failed to update password',
+      );
+    } catch (e) {
+      return UserResult(success: false, error: 'Network error: $e');
+    }
+  }
+
+  /// Delete a user (Admin only)
+  Future<UserResult> deleteUser(String userId) async {
+    try {
+      _api.restoreToken();
+      final response = await _api.delete('/api/users/$userId');
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        return UserResult(success: true);
+      }
+      return UserResult(
+        success: false,
+        error: data['error'] as String? ?? 'Failed to delete user',
+      );
+    } catch (e) {
+      return UserResult(success: false, error: 'Network error: $e');
+    }
+  }
+
+  /// Toggle admin status (Admin only)
+  Future<UserResult> toggleAdmin(String userId, bool isAdmin) async {
+    try {
+      _api.restoreToken();
+      final response = await _api.put('/api/users/$userId', data: {
+        'isAdmin': isAdmin,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        return UserResult(success: true);
+      }
+      return UserResult(
+        success: false,
+        error: data['error'] as String? ?? 'Failed to update user',
+      );
+    } catch (e) {
+      return UserResult(success: false, error: 'Network error: $e');
+    }
+  }
+}
+
+/// Result of user operation
+class UserResult {
+  final bool success;
+  final AppUser? user;
+  final String? error;
+
+  UserResult({
+    required this.success,
+    this.user,
+    this.error,
+  });
+}