Aggiunge il rilevamento di invio e apertura delle email di campagna.

Ogni destinatario mostra se la mail è partita e se è stata aperta, con conteggi in dashboard.

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

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2026_08_17_234500) do
+ActiveRecord::Schema[8.1].define(version: 2026_08_20_110000) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
 
@@ -126,17 +126,23 @@ ActiveRecord::Schema[8.1].define(version: 2026_08_17_234500) do
     t.datetime "created_at", null: false
     t.string "email"
     t.text "error_message"
+    t.datetime "last_opened_at"
     t.bigint "mailing_id", null: false
+    t.integer "open_count", default: 0, null: false
+    t.datetime "opened_at"
     t.bigint "organization_id", null: false
     t.string "rendered_subject"
     t.datetime "sent_at"
     t.string "skip_reason"
     t.string "status", default: "pending", null: false
+    t.string "tracking_token", null: false
     t.datetime "updated_at", null: false
     t.index ["ab_variant"], name: "index_mailing_recipients_on_ab_variant"
     t.index ["email"], name: "index_mailing_recipients_on_email"
     t.index ["mailing_id", "organization_id"], name: "idx_mailing_recipients_unique", unique: true
+    t.index ["opened_at"], name: "index_mailing_recipients_on_opened_at"
     t.index ["status"], name: "index_mailing_recipients_on_status"
+    t.index ["tracking_token"], name: "index_mailing_recipients_on_tracking_token", unique: true
   end
 
   create_table "mailings", force: :cascade do |t|