nostr publish event fix

lib/data/session/models/user.dart

@@ -20,6 +20,10 @@ class User {
   /// Optional Nostr profile data (if logged in via Nostr).
   final NostrProfile? nostrProfile;
 
+  /// Optional Nostr private key (nsec) if logged in with nsec.
+  /// This is stored to enable event publishing. Only set if user logged in with nsec.
+  final String? nostrPrivateKey;
+
   /// Creates a [User] instance.
   /// 
   /// [id] - Unique identifier for the user.
@@ -27,12 +31,14 @@ class User {
   /// [token] - Optional authentication token.
   /// [createdAt] - Session creation timestamp (defaults to current time).
   /// [nostrProfile] - Optional Nostr profile data.
+  /// [nostrPrivateKey] - Optional Nostr private key (nsec) for event publishing.
   User({
     required this.id,
     required this.username,
     this.token,
     int? createdAt,
     this.nostrProfile,
+    this.nostrPrivateKey,
   }) : createdAt = createdAt ?? DateTime.now().millisecondsSinceEpoch;
 
   /// Creates a [User] from a Map (e.g., from database or JSON).
@@ -45,6 +51,7 @@ class User {
       nostrProfile: map['nostr_profile'] != null
           ? NostrProfile.fromJson(map['nostr_profile'] as Map<String, dynamic>)
           : null,
+      nostrPrivateKey: map['nostr_private_key'] as String?,
     );
   }
 
@@ -56,6 +63,7 @@ class User {
       'token': token,
       'created_at': createdAt,
       'nostr_profile': nostrProfile?.toJson(),
+      'nostr_private_key': nostrPrivateKey,
     };
   }
 
@@ -66,6 +74,7 @@ class User {
     String? token,
     int? createdAt,
     NostrProfile? nostrProfile,
+    String? nostrPrivateKey,
   }) {
     return User(
       id: id ?? this.id,
@@ -73,6 +82,7 @@ class User {
       token: token ?? this.token,
       createdAt: createdAt ?? this.createdAt,
       nostrProfile: nostrProfile ?? this.nostrProfile,
+      nostrPrivateKey: nostrPrivateKey ?? this.nostrPrivateKey,
     );
   }