Implement a nix build and development environment

[simoninns]

ld-decode should be wrapped in nix.

Wrapping ld-decode with Nix will provide a declarative, reproducible, and isolated development and production environment, effectively solving the "it works on my machine" problem.

Instead of relying on mutable system-wide installations or complex setup instructions, Nix would pin all dependencies—from libraries to compilers—ensuring the project runs identically across different machines and over time.

Nix can be installed on just about any Linux distro and even sub-standard unix-like systems such as MacOS