feat: added devshell default input template for nix projects

flake.nix

@@ -59,6 +59,7 @@
 
       alias = {
         shells.default = "yumeami";
+        templates.default = "devshell";
       };
     };
 }

templates/devshell/flake.nix

@@ -0,0 +1,43 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-25.05";
+    flake-utils.url = "github:numtide/flake-utils";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
+  };
+  outputs = {
+    flake-utils,
+    nixpkgs,
+    treefmt-nix,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = import nixpkgs {inherit system;};
+
+        treefmtConfig = {...}: {
+          projectRootFile = "flake.nix";
+          programs = {
+            alejandra.enable = true;
+          };
+        };
+
+        treefmtEval = treefmt-nix.lib.evalModule pkgs (treefmtConfig {inherit pkgs;});
+      in {
+        formatter = treefmtEval.config.build.wrapper;
+
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = with pkgs; [
+          ];
+
+          buildInputs = with pkgs; [
+          ];
+
+          packages = with pkgs; [
+          ];
+
+          shellHook = ''
+          '';
+        };
+      }
+    );
+}