...such as flake files or {shell,default}.nix to reduce the necessity to
rebuild (when using `nix build`) after each change, even to non-go
files. more files can be added to an exclude list in the future.
* reformat the flake
* create a fyne application, specify deps as both buildGoModule
buildInputs and packages in devShells
* add nixGL overlay to devShells so that openGL-based apps (such as fyne
apps) run fine for non-NixOS users
* add build/link flags