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/activity.rb

@@ -0,0 +1,18 @@
+class Activity < ApplicationRecord
+  include Auditable
+
+  belongs_to :user, optional: true
+  belongs_to :organization
+  belongs_to :contact, optional: true
+  belongs_to :opportunity, optional: true
+
+  validates :activity_type, inclusion: { in: Catalog::ACTIVITY_TYPES.keys }
+  validates :subject, :happened_at, presence: true
+
+  scope :recent_first, -> { order(happened_at: :desc, id: :desc) }
+  scope :chronological, -> { order(happened_at: :asc, id: :asc) }
+
+  def activity_type_label
+    Catalog.label_for(Catalog::ACTIVITY_TYPES, activity_type)
+  end
+end