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>

db/migrate/20260817120000_allow_null_activity_user_id.rb

@@ -0,0 +1,5 @@
+class AllowNullActivityUserId < ActiveRecord::Migration[8.1]
+  def change
+    change_column_null :activities, :user_id, true
+  end
+end