fix(app): make AuthUser.email nullable, add phone field

Phone-invited users have null email — casting null to String crashed login.
email: String → String?, added phone: String? to AuthUser and AuthUserEntity.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

it0_app/lib/features/auth/data/models/auth_response.dart

@@ -20,14 +20,16 @@ class AuthResponse {
 
 class AuthUser {
   final String id;
-  final String email;
+  final String? email;
+  final String? phone;
   final String name;
   final List<String> roles;
   final String? tenantId;
 
   const AuthUser({
     required this.id,
-    required this.email,
+    this.email,
+    this.phone,
     required this.name,
     required this.roles,
     this.tenantId,
@@ -36,7 +38,8 @@ class AuthUser {
   factory AuthUser.fromJson(Map<String, dynamic> json) {
     return AuthUser(
       id: json['id'] as String,
-      email: json['email'] as String,
+      email: json['email'] as String?,
+      phone: json['phone'] as String?,
       name: json['name'] as String,
       roles: (json['roles'] as List).cast<String>(),
       tenantId: json['tenantId'] as String?,

it0_app/lib/features/auth/data/repositories/auth_repository_impl.dart

@@ -33,6 +33,7 @@ class AuthRepositoryImpl implements AuthRepository {
     return AuthUserEntity(
       id: response.user.id,
       email: response.user.email,
+      phone: response.user.phone,
       name: response.user.name,
       roles: response.user.roles,
     );
@@ -78,6 +79,7 @@ class AuthRepositoryImpl implements AuthRepository {
       return AuthUserEntity(
         id: user.id,
         email: user.email,
+        phone: user.phone,
         name: user.name,
         roles: user.roles,
       );

it0_app/lib/features/auth/domain/entities/auth_user.dart

@@ -1,7 +1,8 @@
 /// Domain entity representing an authenticated user.
 class AuthUserEntity {
   final String id;
-  final String email;
+  final String? email;
+  final String? phone;
   final String name;
   final List<String> roles;
   final String? tenantId;
@@ -9,7 +10,8 @@ class AuthUserEntity {
 
   const AuthUserEntity({
     required this.id,
-    required this.email,
+    this.email,
+    this.phone,
     required this.name,
     required this.roles,
     this.tenantId,