feat: add installation with nix flake

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1761907660,
+        "narHash": "sha256-kJ8lIZsiPOmbkJypG+B5sReDXSD1KGu2VEPNqhRa/ew=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "2fb006b87f04c4d3bdf08cfdbc7fab9c13d94a15",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,48 @@
+{
+  description = "Gruvbox-inspired wallpaper collection";
+
+  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+  outputs = {
+    self,
+    nixpkgs,
+  }: let
+    systems = ["x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin"];
+    forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f (import nixpkgs {inherit system;}));
+
+    mkWallpapersPkg = pkgs: name: path:
+      pkgs.stdenv.mkDerivation {
+        pname = "gruvbox-wallpapers-${name}";
+        version = self.shortRev or "dev";
+        src = ./.;
+        installPhase = ''
+          mkdir -p $out
+          ${
+            if name == "default"
+            then "find wallpapers -type f -exec cp {} $out/ \\;"
+            else "cp -r ${path}/* $out/"
+          }
+        '';
+      };
+
+    subdirs = {
+      default = "wallpapers";
+      anime = "wallpapers/anime";
+      brands = "wallpapers/brands";
+      game = "wallpapers/game";
+      minimalistic = "wallpapers/minimalistic";
+      mix = "wallpapers/mix";
+      painting = "wallpapers/painting";
+      photography = "wallpapers/photography";
+      pixelart = "wallpapers/pixelart";
+      renders = "wallpapers/renders";
+    };
+  in {
+    formatter = forAllSystems (pkgs: pkgs.alejandra);
+
+    packages = forAllSystems (
+      pkgs:
+        nixpkgs.lib.mapAttrs (name: path: mkWallpapersPkg pkgs name path) subdirs
+    );
+  };
+}