fix(snippetz): send the body in http/http1.1 examples for json media types and text bodies - #10510

Problem

The raw HTTP/1.1 code example leaves out the request body unless the media type is exactly application/json, application/octet-stream, a url-encoded form or multipart. A body for application/json; charset=utf-8, application/vnd.api+json, text/plain or application/xml is dropped, so the copied request is sent with a Content-Type header and no body.

Solution

Use the existing isJsonMediaType helper from @scalar/helpers for JSON types and keep the media type as written in the header. Any other body that has text is now sent as it is. Output for plain application/json is the same as before.

I added tests for a charset parameter, a +json type and a plain text body. All three fail without the change.

Checklist

• I explained why the change is needed.
• I added a changeset.
• I added tests.
• I updated the documentation. (not needed, no docs describe this)