Adds a new endpoint that creates a shareable Midtrans Snap payment link
straight from { order_id, nominal, customer, expire_at } without remapping
to the mercant_id/item[] shape required by /createtransaksi.
order_id is sanitized (':' and other disallowed chars -> '.') before being
sent to Midtrans, while the mercant_id used for ERP webhook notification is
derived from the original, unsanitized order_id so ERP always gets a clean
identifier instead of the full composite order_id.
Includes a Postman collection covering link creation, resolution, status
check, and replaying a captured Midtrans notification payload for local
webhook debugging.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
