feat: Initialize XtremFlow project with core structure, IPTV features, authentication, and video player.

lib/core/models/app_user.dart

@@ -0,0 +1,51 @@
+import 'package:hive/hive.dart';
+
+part 'app_user.g.dart';
+
+@HiveType(typeId: 0)
+class AppUser {
+  @HiveField(0)
+  final String id;
+
+  @HiveField(1)
+  final String username;
+
+  @HiveField(2)
+  final String passwordHash; // SHA-256 hash
+
+  @HiveField(3)
+  final bool isAdmin;
+
+  @HiveField(4)
+  final List<String> assignedPlaylistIds;
+
+  @HiveField(5)
+  final DateTime createdAt;
+
+  const AppUser({
+    required this.id,
+    required this.username,
+    required this.passwordHash,
+    required this.isAdmin,
+    required this.assignedPlaylistIds,
+    required this.createdAt,
+  });
+
+  AppUser copyWith({
+    String? id,
+    String? username,
+    String? passwordHash,
+    bool? isAdmin,
+    List<String>? assignedPlaylistIds,
+    DateTime? createdAt,
+  }) {
+    return AppUser(
+      id: id ?? this.id,
+      username: username ?? this.username,
+      passwordHash: passwordHash ?? this.passwordHash,
+      isAdmin: isAdmin ?? this.isAdmin,
+      assignedPlaylistIds: assignedPlaylistIds ?? this.assignedPlaylistIds,
+      createdAt: createdAt ?? this.createdAt,
+    );
+  }
+}