Refactor home modules and update printing comments

Add placeholder publishing settings in printing module.

Refactor Codex module to add nodejs to home packages and nest the
program configuration under `config`. Simplify Opencode validation by
removing the TUI validation flag, keeping only `config`.

modules/home/opencode/default.nix

@@ -9,10 +9,7 @@
   config.programs.opencode = lib.mkIf config.opencode.enable {
     enable = true;
     package = pkgs.opencode;
-    validateFiles = {
-      config = true;
-      tui = true;
-    };
+    validateFiles.config = true;
   };
 
   imports = [