Fix checkout Stripe: ricrea customer se ID test su ambiente live.

Evita errore «No such customer» dopo passaggio da sk_test a sk_live.

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

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

@@ -0,0 +1,59 @@
+module Billing
+  module Stripe
+    # Garantisce un Customer Stripe valido per la modalità API attiva (test vs live).
+    class EnsureCustomer
+      def self.call(club:, user:)
+        new(club: club, user: user).call
+      end
+
+      def initialize(club:, user:)
+        @club = club
+        @user = user
+      end
+
+      def call
+        sub = @club.subscription || @club.build_subscription(plan: Plan["free"], status: "active")
+
+        if sub.stripe_customer_id.present? && !customer_valid?(sub.stripe_customer_id)
+          reset_stripe_billing!(sub)
+        end
+
+        return sub.stripe_customer_id if sub.stripe_customer_id.present?
+
+        customer = ::Stripe::Customer.create(
+          email: billing_email,
+          name: @club.billing_legal_name.presence || @club.name,
+          metadata: { club_id: @club.id }
+        )
+        sub.update!(stripe_customer_id: customer.id)
+        customer.id
+      end
+
+      private
+
+      def billing_email
+        @club.billing_email.presence || @user.email
+      end
+
+      def customer_valid?(customer_id)
+        ::Stripe::Customer.retrieve(customer_id)
+        true
+      rescue ::Stripe::InvalidRequestError => e
+        return false if e.code == "resource_missing" || e.message.include?("No such customer")
+
+        raise
+      end
+
+      def reset_stripe_billing!(sub)
+        Rails.logger.info(
+          "[Stripe] Customer #{sub.stripe_customer_id} non valido per club #{@club.id} — reset ID Stripe locali"
+        )
+        sub.update!(
+          stripe_customer_id: nil,
+          stripe_subscription_id: nil,
+          cancel_at_period_end: false
+        )
+      end
+    end
+  end
+end