Enhancement: Add Neo client

Whilst it hasn't seen development for a while (the last commit in `main` was on 09/09/24), I think we should add it to the list of clients for the sake of completeness. For clarification, this issue refers to [Neo](https://github.com/alexispurslane/neo), not [NeoChat](https://matrix.org/ecosystem/clients/neochat/).

Read the website's existing Matrix client listings and locate where clients are catalogued. Confirm the linked Neo project is distinct from NeoChat and assess whether it still belongs in the list; done means Neo is added consistently with the existing entries.

Written by the indexing model from the issue text.