Update to (somewhat?) dendritic pattern

Heavily inspired by https://github.com/Doc-Steve/dendritic-design-with-flake-parts.

> Atomic commits? Never heard of them!

modules/programs/development-tools/development-tools.nix

@@ -0,0 +1,14 @@
+{ inputs, ... }: {
+  flake.modules.nixos.development-tools = { pkgs, ... }: {
+    imports = with inputs.self.modules.nixos; [
+      rust
+    ];
+
+    environment.systemPackages = with pkgs; [
+      cmake
+      gnumake
+      clang
+      gcc
+    ];
+  };
+}

modules/programs/development-tools/rust.nix

@@ -0,0 +1,18 @@
+{ inputs, ... }: {
+  flake-file.inputs = {
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  flake.modules.nixos.rust = { pkgs, ... }: {
+    nixpkgs.overlays = [
+      inputs.rust-overlay.overlays.default
+    ];
+
+    environment.systemPackages = with pkgs; [
+      rust-bin.stable.latest.default
+    ];
+  };
+}