NixOS dev environment

Note: this is not used in production.

To get a shell with this env:

$ nix-shell

To run a command in this env, you can’t use nix-shell --run, but instead:

$ NIX_SHELL_RUN='...' nix-shell

To set up clangd with remote indexing support:

1. $ NIX_SHELL_RUN='readlink /usr/bin/clangd' nix-shell
2. Copy the path into your editor config