Shipment notification sent on state transition to shipped

A shipment notification that omits tracking information is worse than no notification at all: it tells the customer the package has left the warehouse but gives them nothing to act on. Without tracking data in the email, the customer must contact support or log in to the account page to find the tracking number — and if they can't find it, the next call is to their credit card company. This is an iso-25010:2011 reliability gap: the email was sent but failed to deliver the information that makes it useful. The tracking number and carrier captured at the 'shipped' transition (see tracking-info) must flow directly into the email template.

Wire the shipment notification into lib/orders/shipping.ts so the tracking data captured at ship time is passed directly to the email in lib/email/order-emails.ts.

// lib/email/order-emails.ts
export async function sendShipmentNotificationEmail(params: {
  to: string
  orderNumber: string
  trackingNumber: string
  carrier: string
  trackingUrl: string
}) {
  await emailService.send({
    to: params.to,
    subject: `Your order ${params.orderNumber} has shipped`,
    template: 'shipment-notification',
    data: params,
  })
}

// In markOrderShipped() (lib/orders/shipping.ts):
await sendShipmentNotificationEmail({
  to: order.user.email,
  orderNumber: order.id,
  trackingNumber,
  carrier,
  trackingUrl: `https://yoursite.com/orders/${order.id}/track`,
})