Admin fatturazione: coda pagamenti senza PDF e upload diretto.

Lista globale dei pagamenti da fatturare con dati intestazione, caricamento
PDF per riga che crea la fattura e invia email; rimuove il flusso bozza manuale.

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

backend/app/models/billing/payment.rb

@@ -14,6 +14,41 @@ module Billing
 
     scope :recent, -> { order(paid_at: :desc, created_at: :desc) }
 
+    # Pagamenti pagati senza PDF fattura caricato (da gestire in admin).
+    scope :awaiting_invoice_pdf, lambda {
+      where(status: "paid").where(
+        <<~SQL.squish,
+          NOT EXISTS (
+            SELECT 1 FROM billing_invoices bi
+            INNER JOIN active_storage_attachments asa
+              ON asa.record_type = 'Billing::Invoice'
+              AND asa.record_id = bi.id
+              AND asa.name = 'pdf'
+            WHERE bi.billing_payment_id = billing_payments.id
+          )
+        SQL
+      )
+    }
+
+    scope :with_invoice_pdf, lambda {
+      where(status: "paid").where(
+        <<~SQL.squish,
+          EXISTS (
+            SELECT 1 FROM billing_invoices bi
+            INNER JOIN active_storage_attachments asa
+              ON asa.record_type = 'Billing::Invoice'
+              AND asa.record_id = bi.id
+              AND asa.name = 'pdf'
+            WHERE bi.billing_payment_id = billing_payments.id
+          )
+        SQL
+      )
+    }
+
+    def awaiting_invoice_pdf?
+      status == "paid" && !invoice&.pdf&.attached?
+    end
+
     def amount_euros
       amount_cents / 100.0
     end