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/system-types/base/homeManager.nix

@@ -0,0 +1,9 @@
+{ inputs, ... }: {
+  flake.modules.homeManager.system-base = { config, ... }: {
+    imports = with inputs.self.modules.homeManager; [
+    ];
+
+    home.homeDirectory = "/home/${config.home.username}";
+    home.stateVersion = "25.11";
+  };
+}

modules/system-types/base/nixos.nix

@@ -0,0 +1,65 @@
+{ inputs, ... }: {
+  flake-file.inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
+    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
+  };
+
+  flake.modules.nixos.system-base = { pkgs, ... }: {
+    imports = with inputs.self.modules.nixos; [
+      home-manager
+      secrets
+      openssh
+      linux-latest
+      cli-tools
+      zsh
+      gnupg
+    ];
+
+    # Make unstable nixpkgs available as pkgs.unstable
+    nixpkgs.overlays = [
+      (final: _prev: {
+        unstable = import inputs.nixpkgs-unstable {
+          inherit (final) config;
+          system = pkgs.stdenv.hostPlatform.system;
+        };
+      })
+    ];
+    nixpkgs.config.allowUnfree = true;
+
+    nix.gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 7d";
+    };
+
+    nix.settings = {
+      substituters = [
+        # high priority since it's almost always used
+        "https://cache.nixos.org?priority=10"
+        "https://install.determinate.systems"
+        "https://nix-community.cachix.org"
+      ];
+
+      trusted-public-keys = [
+        "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+        "cache.flakehub.com-3:hJuILl5sVK4iKm86JzgdXW12Y2Hwd5G07qKtHTOcDCM"
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      ];
+
+      experimental-features = [
+        "nix-command"
+        "flakes"
+        # "allow-import-from-derivation"
+      ];
+
+      download-buffer-size = 1024 * 1024 * 1024;
+
+      trusted-users = [
+        "root"
+        "@wheel"
+      ];
+    };
+
+    system.stateVersion = "25.11";
+  };
+}