SellerAccountUnverifiedException (403) when creating product-based offer via POST /sale/product-offers on production

### Description

When creating the first product-based offer on **production** via `POST /sale/product-offers` (path 02 - creating a new product, sending full `product` data without `product.id`), the API returns **HTTP 403** with `SellerAccountUnverifiedException`.

The same request works correctly on **Sandbox** (offers are created successfully).

### Endpoint

`POST /sale/product-offers`

### Environment

- Production (api.allegro.pl)
- Marketplaces: allegro-cz

### Response received (403)

```json
{
"errors": [
{
"code": "SellerAccountUnverifiedException",
"message": "Product proposal unauthorized according to unverified account.",
"details": null,
"path": "productSet[0].product",
"userMessage": "Użytkownik z nieaktywnym lub niezweryfikowanym kontem nie może zgłaszać nowych propozycji utworzenia produktu.",
"metadata": {}
}
]
}
```

### What we are trying to do

We are listing a product (with its full description: name, category, parameters, images) as a new offer, without sending `product.id`, so that Allegro creates the catalog product if it does not exist yet (path "02 - when you want to create a new product or you are not sure whether the product exists in the Product Catalog").

### Questions

We have already verified the seller account and checked all account settings - the account is active, verified, and enabled for selling. Despite this, `POST /sale/product-offers` (path 02, full `product` without `product.id`) still returns `SellerAccountUnverifiedException` (403) on production.

1. Since our account appears to be fully verified and active, what specifically causes the `SellerAccountUnverifiedException` in this case? Is there an additional verification or permission - separate from standard seller account verification - that is specifically required to create **new catalog product proposals**?
2. How can we identify, from our side, which exact requirement is missing on the account? Is there an endpoint or account setting we can check to see the status of this specific permission?
3. What concrete steps do we need to take to resolve this and be able to create the offer, given that the standard account verification is already completed?

### Additional info

- Authentication and token flow work correctly (other GET endpoints respond normally).
- The request payload is validated successfully on Sandbox (no validation errors), so we believe the request structure is correct and the issue is account-related on production.