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/controllers/admin/auth_controller.rb

@@ -10,16 +10,16 @@ module Admin
       account = AdminAccount.find_by(username: params[:username]&.strip)
       if account&.authenticate(params[:password])
         session[:admin_account_id] = account.id
-        redirect_to session.delete(:admin_return_to) || admin_root_path, notice: "Accesso effettuato"
+        redirect_to session.delete(:admin_return_to) || admin_root_path, notice: t("admin.flash.login_success")
       else
-        flash.now[:alert] = "Username o password non validi"
+        flash.now[:alert] = t("admin.flash.invalid_credentials")
         render :new, status: :unauthorized
       end
     end
 
     def destroy
       reset_session
-      redirect_to admin_login_path, notice: "Disconnesso"
+      redirect_to admin_login_path, notice: t("admin.flash.logout_success")
     end
   end
 end