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/config/routes.rb

@@ -63,6 +63,7 @@ Rails.application.routes.draw do
     root to: "dashboard#index"
     get "metrics", to: "dashboard#metrics"
     get "billing", to: "billing#index", as: :billing
+    post "billing/payments/:payment_id/attach_pdf", to: "billing#attach_pdf", as: :billing_payment_attach_pdf
     resources :teams, only: %i[index show]
     resources :clubs, only: [] do
       resources :billing_invoices, only: %i[index new create edit update], controller: "billing_invoices"