Aggiunge abbonamenti omaggio admin per sponsor e promozioni.

Gli admin possono concedere o revocare Premium Light/Full senza Stripe;
il piano omaggio ha priorità sui webhook e la società vede un messaggio dedicato.

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

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

@@ -18,6 +18,7 @@ module Billing
         raise "Stripe non configurato" unless MatchLiveTv.stripe_enabled?
         raise "Piano non valido" unless VALID_PLANS.include?(@plan_slug)
 
+        raise "Abbonamento omaggio: contatta il supporto per cambiare piano a pagamento" if @sub&.admin_comped?
         raise "Nessun abbonamento Stripe attivo" if @sub.blank? || @sub.stripe_subscription_id.blank?
 
         interval = resolve_interval(@sub)

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

@@ -70,6 +70,8 @@ module Billing
                            PriceCatalog::DEFAULT_INTERVAL
 
         sub = club.subscription
+        return sub if sub&.admin_comped?
+
         clear_pending = sub&.pending_plan_id.present? &&
                         (sub.pending_plan.slug == plan.slug || infer_plan_slug_from_price(stripe_sub) == sub.pending_plan.slug)
 

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

@@ -14,6 +14,7 @@ module Billing
         sub = @club.subscription
         return false unless sub&.stripe_subscription_id.present?
         return false if sub.free?
+        return false if sub.admin_comped?
 
         stripe_sub = ::Stripe::Subscription.retrieve(sub.stripe_subscription_id)