implemented a guided notification permission flow triggered on the first Talk visit

lib/storage/notification_settings.dart

@@ -5,12 +5,21 @@ part 'notification_settings.g.dart';
 @JsonSerializable()
 class NotificationSettings {
   /// Whether push notifications are enabled. Defaults to `true` — the OS
-  /// permission prompt at login is now the gate, so there is no separate
-  /// in-app opt-in step anymore.
+  /// permission prompt on the first Talk visit is now the gate, so there is no
+  /// separate in-app opt-in step anymore.
   @JsonKey(defaultValue: true)
   bool enabled;
 
-  NotificationSettings({this.enabled = true});
+  /// Whether the one-time notification-permission prompt shown on the first
+  /// Talk visit has already run. Prevents nagging the user on every visit and
+  /// keeps the OS prompt out of the cold-start path.
+  @JsonKey(defaultValue: false)
+  bool talkPermissionPromptShown;
+
+  NotificationSettings({
+    this.enabled = true,
+    this.talkPermissionPromptShown = false,
+  });
 
   factory NotificationSettings.fromJson(Map<String, dynamic> json) =>
       _$NotificationSettingsFromJson(json);

lib/storage/notification_settings.g.dart

@@ -8,8 +8,15 @@ part of 'notification_settings.dart';
 
 NotificationSettings _$NotificationSettingsFromJson(
   Map<String, dynamic> json,
-) => NotificationSettings(enabled: json['enabled'] as bool? ?? true);
+) => NotificationSettings(
+  enabled: json['enabled'] as bool? ?? true,
+  talkPermissionPromptShown:
+      json['talkPermissionPromptShown'] as bool? ?? false,
+);
 
 Map<String, dynamic> _$NotificationSettingsToJson(
   NotificationSettings instance,
-) => <String, dynamic>{'enabled': instance.enabled};
+) => <String, dynamic>{
+  'enabled': instance.enabled,
+  'talkPermissionPromptShown': instance.talkPermissionPromptShown,
+};