Receivables payment settings (enabled methods + live Stripe Connect status)

Wave 3b (#1153/#1154) + AR charge rail. DARK — 404s unless ar_ap_items_enabled. Returns the merchant-configurable collection methods (card via Stripe Connect, bank transfer / ACH-wire) plus the LIVE Stripe Connect onboarding status derived from stripe_connections — never a stored connected flag. Shape: { available, feeMode: absorb|pass, methods: { card: { enabled, connected, rail: "stripe_connect" }, bankTransfer: { enabled, detailsStatus: not_provided|pending|provided, instructions } }, bankAccount: { accountHolderName, bankName, routingNumber, accountNumber, accountType, swiftBic, wireInstructions }, stripeConnect: { status, connected, accountId (masked ****1234 or null), livemode, lastSyncAt }, updatedAt }. The bankAccount block is the structured receiving-account detail; the sensitive fields (routingNumber, accountNumber, swiftBic) are ALWAYS masked to ****1234 on read — clear values never leave the API on this surface. The public pay page offers bank transfer only when bankTransfer.enabled AND the four payer-required bankAccount fields (holder, bank, routing, account) are present.