[lsp-server] 🐞 Descriptions on query variables not working yet

### Is there an existing issue for this? - [x] I have searched the existing issues ### Current Behavior Currently, descriptions on query variables cause an error: <img width="871" height="282" alt="Image" src="https://github.com/user-attachments/assets/b89baed6-5e7e-4125-b12a-e96703688be2" /> ### Expected Behavior According to https://github.com/graphql/graphql-spec/pull/1170, the comment should not error. ### Steps To Reproduce Reproduction here: https://graphql.org/swapi-graphql/?query=%22%22%22Foo%22%22%22%0Aquery%20Foo%20(%0A%20%20%20%20%22%22%22%0A%20%20%20%20Argument-Level%20Comment%20Test%0A%20%20%20%20%22%22%22%0A%20%20%20%20%24test%3A%20Boolean!%0A)%20%7B%0A%20%20__typename%20%40include(if%3A%20%24test)%0A%7D&operationName=Foo ### Environment * LSP Server Version:5.5.0 * OS: OSX * LSP Client: GraphiQL ### Anything else? _No response_