add start/business unit

lib/features/auth/domain/entities/business_unit.dart

@@ -0,0 +1,93 @@
+/// Domain Entity: Business Unit
+///
+/// Represents a business unit that a user can access.
+library;
+
+/// Business Unit Entity
+///
+/// Represents a business division or unit that a user has access to.
+class BusinessUnit {
+  /// Unique business unit identifier
+  final String id;
+
+  /// Business unit code (e.g., "VIKD", "HSKD", "LPKD")
+  final String code;
+
+  /// Display name
+  final String name;
+
+  /// Description
+  final String? description;
+
+  /// Whether this is the default unit
+  final bool isDefault;
+
+  const BusinessUnit({
+    required this.id,
+    required this.code,
+    required this.name,
+    this.description,
+    this.isDefault = false,
+  });
+
+  /// Create from JSON map
+  factory BusinessUnit.fromJson(Map<String, dynamic> json) {
+    return BusinessUnit(
+      id: json['id'] as String,
+      code: json['code'] as String,
+      name: json['name'] as String,
+      description: json['description'] as String?,
+      isDefault: json['is_default'] as bool? ?? false,
+    );
+  }
+
+  /// Convert to JSON map
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'code': code,
+      'name': name,
+      'description': description,
+      'is_default': isDefault,
+    };
+  }
+
+  /// Copy with method for immutability
+  BusinessUnit copyWith({
+    String? id,
+    String? code,
+    String? name,
+    String? description,
+    bool? isDefault,
+  }) {
+    return BusinessUnit(
+      id: id ?? this.id,
+      code: code ?? this.code,
+      name: name ?? this.name,
+      description: description ?? this.description,
+      isDefault: isDefault ?? this.isDefault,
+    );
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+
+    return other is BusinessUnit &&
+        other.id == id &&
+        other.code == code &&
+        other.name == name &&
+        other.description == description &&
+        other.isDefault == isDefault;
+  }
+
+  @override
+  int get hashCode {
+    return Object.hash(id, code, name, description, isDefault);
+  }
+
+  @override
+  String toString() {
+    return 'BusinessUnit(id: $id, code: $code, name: $name, isDefault: $isDefault)';
+  }
+}