refactor: move common variables referenced into common/variables.nix

In the future, should have independent variable files for home-manager and nixos-specific,

in their respective directories.

common/variables.nix

@@ -0,0 +1,27 @@
+{
+  tmconfig,
+  pkgs,
+  lib,
+  ...
+}: {
+  # Type definitions for nix variables used in this configuration
+  options = with lib;
+  with types; {
+    myUserName = mkOption {type = str;};
+    myHostName = mkOption {type = str;};
+    myWallPaperPathString = mkOption {type = str;};
+    myDisplayName = mkOption {type = str;};
+    myEmail = mkOption {type = str;};
+    displayScale = mkOption {type = int;};
+  };
+
+  # Default values for this configuration
+  config = rec {
+    myUserName = "stvnliu";
+    myHostName = "homelab-nix";
+    displayScale = 2;
+    myWallPaperPathString = "/home/${myUserName}/wallpaper.png";
+    myDisplayName = "Zhongheng Liu";
+    myEmail = "z.liu@outlook.com.gr";
+  };
+}

home-manager/stvnliu/home.nix

@@ -16,7 +16,7 @@
     #./swaywm.nix
     ./hypr
     ./shells
-    ./variables.nix
+    ../../common/variables.nix
     ./mako.nix
     ./wechat
     ./editors.nix

nixos/variables.nix

@@ -1,19 +0,0 @@
-{
-  config,
-  pkgs,
-  lib,
-  ...
-}: {
-  # Type definitions for nix variables used in this configuration
-  options = with lib;
-  with types; {
-    myUserName = mkOption {type = str;};
-    myHostName = mkOption {type = str;};
-  };
-
-  # Default values for this configuration
-  config = {
-    myUserName = "stvnliu";
-    myHostName = "homelab-nix";
-  };
-}