Commit iniziale di eminuxCRM: CRM Rails con pipeline, campagne email e Docker.

Include autenticazione, progetti isolati, mail marketing HTML con SMTP, test A/B e editor WYSIWYG.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/models/concerns/auditable.rb

@@ -0,0 +1,21 @@
+module Auditable
+  extend ActiveSupport::Concern
+
+  included do
+    belongs_to :created_by, class_name: "User", optional: true
+    belongs_to :updated_by, class_name: "User", optional: true
+
+    before_create :set_created_by
+    before_save :set_updated_by
+  end
+
+  private
+
+  def set_created_by
+    self.created_by_id ||= Current.user&.id
+  end
+
+  def set_updated_by
+    self.updated_by_id = Current.user&.id if Current.user
+  end
+end