[BUG] image upload for customized-products example doesn't work

[mkucmus]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

/store-api/customized-products/upload returns

{
    "errors": [
        {
            "code": "0",
            "status": "400",
            "title": "Bad Request",
            "detail": "The JSON payload is malformed."
        }
    ]
}

but there is no json sent, but multipart form data

Expected Behavior

I'm able to send an image

Acceptance criteria

• an image can be uploaded
• examples is migrated to nuxt

Steps To Reproduce

run an example and try to upload a file
No response

Environment

- OS:
- Node:
- pnpm:

Anything else?

No response

[mkucmus]

there is an internal MR in the plugin's repository customized-product/-/merge_requests/570 to make it working