Adding new CD/CI system from dev to prod

[Rizary]

I am in the middle of working on something similar to this repo. Then I thought it will be nice if I just move all my work into todomvc-nix.

My idea is to add the new Flake system, and GitHub action into the repo so every newcomer to Nix language can use this repo as their starting project.

To add some notes, I see some new posts on using Nix and Bazel together into the project, and some people found it too difficult to integrate it. I am planning to add into this repo, what do you think?