move tmux into its one file

modules/cli/default.nix

@@ -9,7 +9,6 @@
     ncdu
     nixpkgs-fmt
     ranger
-    tmux
     tree
     unzip
     vim

modules/common/default.nix

@@ -2,6 +2,7 @@
 {
   imports = [
     (import "${inputs.self}/modules/cli" { inherit inputs pkgs system; })
+    (import "${inputs.self}/modules/tmux" { inherit inputs pkgs system; })
   ];
 
   # The rough location

modules/tmux/default.nix

@@ -0,0 +1,9 @@
+{ pkgs, ... }:
+{
+  programs.tmux = {
+    enable = true;
+    extraConfig = ''
+      set -g mouse on
+    '';
+  };
+}