Read a customer's subscriptions or find existing Stripe subscriptions

Requires the existing manage:contacts permission and a live customer in the selected company. Uses only that company's Stripe account, never its accountant's account. view=search requires integrationId and query (name/email, cus_ ID, or sub_ ID); returns results (id, customer, subscription, linked) and nextPage. view=portal returns the current private portal link and expiry, or null. view=invoices returns invoices (id, number, subscriptionName, createdAt, amountCents, currency, status, invoiceUrl, pdfUrl) and nextCursor. Amounts are integer minor units (US cents). The full invoice is excluded when any line belongs to another billing recipient. Continue with cursor until nextCursor is null.