refactor: make available_only_for_statuses private

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EdWS7o3htQ9cNxhCWL5Frp

Author: claude

lib/seam/base_resource.rb

@@ -84,6 +84,7 @@ def self.available_only_for_statuses(attr, statuses)
           statuses.include?(status) ? unscoped.bind_call(self) : nil
         end
       end
+      private_class_method :available_only_for_statuses
 
       def self.resource_accessors
         @resource_accessors ||= {}