build: added shell.nix

shell.nix

@@ -0,0 +1,31 @@
+let
+    nixpkgs-unstable = builtins.fetchTarball "https://github.com/NixOS/nixpkgs/archive/refs/heads/nixos-unstable.tar.gz";
+
+    pkgs = import <nixpkgs> {};
+    pkgs-unstable = import nixpkgs-unstable {};
+
+in
+
+pkgs.mkShell {
+    nativeBuildInputs = [
+        pkgs-unstable.rustc
+        pkgs-unstable.cargo
+        pkgs-unstable.clippy
+
+        pkgs.gcc
+        pkgs.cmake
+        pkgs.pkg-config
+    ];
+
+    buildInputs = [
+        pkgs.gtk4
+        pkgs.glib
+        pkgs.gdk-pixbuf
+        pkgs.gobject-introspection
+
+        pkgs.libadwaita
+    ];
+
+    RUST_SRC_PATH = "${pkgs-unstable.rust.packages.stable.rustPlatform.rustLibSrc}";
+    RUST_BACKTRACE = 1;
+}