emacs: add missing tangle directive for org-window-habit

The org-window-habit use-package block had no :tangle header, so it
was never written to org-config-config.el. This meant the mode was
never activated and the advice on org-habit-parse-todo was never
installed, causing errors for habits without a scheduled repeater.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dotfiles/emacs.d/org-config.org

@@ -1131,7 +1131,7 @@ alphanumeric characters only."
   :commands org-ql-find-in-agenda)
 #+end_src
 ** org-window-habit
-#+begin_src emacs-lisp
+#+begin_src emacs-lisp :tangle org-config-config.el
 (use-package org-window-habit
   :demand t
   :ensure