refactor(create_headline_state): remove excerpt field

    This commit removes the `excerpt` field from `CreateHeadlineState` and updates
    the `isFormValid` getter, `copyWith` method, and `props` list. This change
    reflects the removal of the `excerpt` field from the `Headline` model in the
    core package.

Author: fulleni

lib/content_management/bloc/create_headline/create_headline_state.dart

@@ -23,7 +23,6 @@ final class CreateHeadlineState extends Equatable {
   const CreateHeadlineState({
     this.status = CreateHeadlineStatus.initial,
     this.title = '',
-    this.excerpt = '',
     this.url = '',
     this.imageUrl = '',
     this.source,
@@ -36,7 +35,6 @@ final class CreateHeadlineState extends Equatable {
 
   final CreateHeadlineStatus status;
   final String title;
-  final String excerpt;
   final String url;
   final String imageUrl;
   final Source? source;
@@ -49,7 +47,6 @@ final class CreateHeadlineState extends Equatable {
   /// Returns true if the form is valid and can be submitted.
   bool get isFormValid =>
       title.isNotEmpty &&
-      excerpt.isNotEmpty &&
       url.isNotEmpty &&
       imageUrl.isNotEmpty &&
       source != null &&
@@ -60,7 +57,6 @@ final class CreateHeadlineState extends Equatable {
   CreateHeadlineState copyWith({
     CreateHeadlineStatus? status,
     String? title,
-    String? excerpt,
     String? url,
     String? imageUrl,
     ValueGetter<Source?>? source,
@@ -73,7 +69,6 @@ final class CreateHeadlineState extends Equatable {
     return CreateHeadlineState(
       status: status ?? this.status,
       title: title ?? this.title,
-      excerpt: excerpt ?? this.excerpt,
       url: url ?? this.url,
       imageUrl: imageUrl ?? this.imageUrl,
       source: source != null ? source() : this.source,
@@ -89,7 +84,6 @@ final class CreateHeadlineState extends Equatable {
   List<Object?> get props => [
     status,
     title,
-    excerpt,
     url,
     imageUrl,
     source,