v2 OAS is inconsistent with documented ecomm_new_order webhook payload

[julianmclain]

There are 2 issues in the v2 OAS definition for the ecomm_new_order webhook:

1. Monetary value fields under OrderAmount (and inline equivalents in extras.price, rowTotal, variantPrice, subtotal, total) are
   declared as type: string. Webflow's documented example payloads use unquoted integers: https://developers.webflow.com/data/reference/all-events#ecomm_new_order.

2. The definition for the disputeLastStatus uses nullable: true which is not supported in OAS 3.1.0. It was removed in favor of the null type.