Completa i18n IT/EN/FR/DE/ES su sito pubblico, area autenticata e admin.

Tutte le view marketing, legali, viewer, dashboard e admin usano t(); mailer utente-facing e flash localizzati; admin con LocaleResolver e selettore lingua.

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

backend/app/mailers/billing/invoice_mailer.rb

@@ -4,15 +4,18 @@ module Billing
       @invoice = params[:invoice]
       @club = @invoice.club
 
-      attachments["fattura-#{@invoice.number.parameterize}.pdf"] = {
-        mime_type: "application/pdf",
-        content: @invoice.pdf.download
-      }
+      I18n.with_locale(I18n.locale) do
+        prefix = t("mailers.invoice.attachment_prefix")
+        attachments["#{prefix}-#{@invoice.number.parameterize}.pdf"] = {
+          mime_type: "application/pdf",
+          content: @invoice.pdf.download
+        }
 
-      mail(
-        to: @club.billing_email,
-        subject: "Fattura #{@invoice.display_number} — Match Live TV"
-      )
+        mail(
+          to: @club.billing_email,
+          subject: t("mailers.invoice.subject", number: @invoice.display_number)
+        )
+      end
     end
   end
 end