Fix: Simplify article author management in Avo

- Remove direct author belongs_to field that was causing NoMethodError
- Organize fields into tabs for better UX
- Manage authors through the authorship association in the Author tab
- Remove custom update_model_record that was interfering with saves

Authors should now be managed through the authorship association:
1. Go to Author tab when editing an article
2. Edit the authorship record
3. Select/change the author there

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: Shpigford

app/avo/resources/article.rb

@@ -10,36 +10,19 @@ class Avo::Resources::Article < Avo::BaseResource
 
   def fields
     field :id, as: :id
-    field :title, as: :text
-    field :slug, as: :text
-    field :content, as: :easy_mde
-    field :publish_at, as: :date_time
     field :author_name, as: :text, hide_on: [ :forms ]
-    field :author, as: :belongs_to, searchable: true, display_with_value: -> { record.name }
 
     tabs do
-      tab "Author Details" do
-        field :authorship, as: :has_one
+      tab "General" do
+        field :title, as: :text
+        field :slug, as: :text
+        field :content, as: :easy_mde
+        field :publish_at, as: :date_time
       end
-    end
-  end
-
-  def update_model_record(model, params, **args)
-    author_id = params.delete(:author_id)
-
-    super(model, params, **args)
 
-    if author_id.present?
-      # Remove existing authorship if present
-      model.authorship&.destroy
-
-      # Create new authorship with the selected author
-      model.create_authorship(author_id: author_id, role: "primary")
-    elsif author_id == ""
-      # If author_id is blank, remove the authorship
-      model.authorship&.destroy
+      tab "Author" do
+        field :authorship, as: :has_one
+      end
     end
-
-    model
   end
 end