Create customer

## Create customer Creates a new customer record scoped to the authenticated merchant's store. The `storeId` is derived from the API key context (not supplied in the body), and a UUID `id` is generated server-side. ### Authentication - Send the merchant API key in the **`x-api-key`** header (alias `x-account-api-key`). - Requires the scope: **`Merchant.customer.create`**. - Optionally scope the key to a specific store/account with the **`x-application-account-id`** header (alias `x-account-id`) or the `application_account_id` / `account_id` query param. ### Body JSON body (`application/json`). Only `name` and `email` are required. The optional fields accepted by `CreateCustomerDto` are `mobile`, `addressLine1`, `addressLine2`, `city`, `state`, `postalCode` and `country`. Unknown properties are stripped by the validation pipe. ### Side-effects / validation - Email must be unique **per store** (case-insensitive). If a customer with the same email already exists for the store, the request fails with **400 Bad Request** (`"A customer with this email already exists for your store."`). - Returns the full persisted customer record on success. --- **Notas:** storeId and id are set server-side and cannot be supplied by the client. Email uniqueness is enforced per store (case-insensitive) and returns 400 on conflict. Related endpoints: GET /v1/customers, PATCH /v1/customers/:id.