Adding `flake.nix` (#363)

* adding nix-flake

adding missing dependencies

flake: adding overlay

flake: adding app

flake: fix package

flake: removing packaging...

adding dev shell

adding overlays

extend devshell for more systems

rust-toolchain: removing rust-src and rust-analyzer

create initial flake state

adding nix build workflow

adding flake lock update ci

nix-build: fix run command

update gitignore

Co-authored-by: RaySlash <RaySlash@users.noreply.github.com>

* fix LD_LIBRARY_PATH for flake

* update paths to nix-build workflows

* adding RaySlash for updating flake

* nix-build: set branch to 0.0.x

* add comment to gitignore

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Co-authored-by: RaySlash <RaySlash@users.noreply.github.com>