Billing: fatture manuali, profilo obbligatorio e piani Stripe mensile/annuale.

Rimuove link al portale Stripe in area cliente, aggiunge flusso admin per PDF
fattura e email, blocca checkout senza dati di fatturazione, allinea prezzi
a €4,90/€39,90 e €9,90/€69,90, locale italiano e documentazione deploy.

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

backend/app/services/billing/stripe/invoice_payment_refs.rb

@@ -0,0 +1,56 @@
+module Billing
+  module Stripe
+    # Estrae riferimenti pagamento da Invoice Stripe (API Basil+: niente payment_intent top-level).
+    module InvoicePaymentRefs
+      EXPAND = ["payments.data.payment.payment_intent"].freeze
+
+      module_function
+
+      def payment_intent_id(invoice)
+        each_payment_intent(invoice) { |pi| stripe_id(pi) }
+      end
+
+      def charge_id(invoice)
+        each_payment_intent(invoice) do |pi|
+          stripe_id(safe_get(pi, :latest_charge))
+        end
+      end
+
+      def each_payment_intent(invoice)
+        payment_entries(invoice).each do |entry|
+          payment = safe_get(entry, :payment)
+          next if payment.blank?
+
+          pi = safe_get(payment, :payment_intent)
+          result = yield(pi) if block_given?
+          return result if result.present?
+        end
+        nil
+      end
+
+      def payment_entries(invoice)
+        payments = safe_get(invoice, :payments)
+        return [] if payments.blank?
+
+        safe_get(payments, :data) || []
+      end
+
+      def stripe_id(value)
+        return nil if value.blank?
+        return value if value.is_a?(String)
+
+        safe_get(value, :id)
+      end
+
+      def safe_get(obj, key)
+        return nil if obj.blank?
+        return obj[key] if obj.is_a?(Hash)
+        return obj.public_send(key) if obj.respond_to?(key)
+
+        nil
+      rescue NoMethodError
+        nil
+      end
+    end
+  end
+end