bitbloxhub’s flake template

A flake template that uses:

• flake-parts to apply the NixOS module system to flakes.
• flake-file for generating the flake.nix.
• import-tree to simplify importing files. Also has npins compat!
• treefmt-nix for formatting with src_bash{nix fmt}.
• make-shell to merge devshell definitions from multiple files with the NixOS module system.
• flint to check your flake inputs for duplicates.
• nixfmt, deadnix, and statix for linting and formatting your Nix code.