refactor: archive old features directory to features.old

The new profile-based structure (home/base, home/desktop, home/server,
home/profiles/, home/coding) is fully operational and imported via
home/lib/mkHomeConfig. The legacy home/features directory is no longer
referenced anywhere in the configuration.

Archived rather than deleted to preserve history for reference.

home/features.old/cli/zellij.nix

@@ -0,0 +1,32 @@
+{
+  config,
+  lib,
+  ...
+}:
+with lib; let
+  cfg = config.features.cli.zellij;
+in {
+  options.features.cli.zellij.enable = mkEnableOption "enable tmux";
+
+  config = mkIf cfg.enable {
+    programs.zellij = {
+      enable = true;
+      settings = {
+        theme = "universal";
+        themes.universal = {
+          bg = "#${config.colorScheme.palette.base00}";
+          fg = "#${config.colorScheme.palette.base05}";
+          black = "#${config.colorScheme.palette.base01}";
+          red = "#${config.colorScheme.palette.base08}";
+          green = "#${config.colorScheme.palette.base0B}";
+          yellow = "#${config.colorScheme.palette.base0A}";
+          blue = "#${config.colorScheme.palette.base0D}";
+          magenta = "#${config.colorScheme.palette.base0E}";
+          cyan = "#${config.colorScheme.palette.base0C}";
+          white = "#${config.colorScheme.palette.base07}";
+          orange = "#${config.colorScheme.palette.base09}";
+        };
+      };
+    };
+  };
+}