feat(scala): Add flake

scala/flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "Scala shell";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    systems.url = "github:nix-systems/default";
+    flake-utils = {
+      url = "github:numtide/flake-utils";
+      inputs.systems.follows = "systems";
+    };
+  };
+
+  outputs = { nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+      in {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            jdk
+            scala-next
+            scala-cli
+
+            # You might want to use your own IDE.
+            (jetbrains.plugins.addPlugins jetbrains.idea-ultimate [ "github-copilot" ])
+          ];
+        };
+      }
+    );
+}