I've set `lexical-binding` to `nil` in all Emacs Lisp files to suppress
the warnings introduced in Emacs 31 requiring all elisp files to have a
`lexical-binding` comment.
This retains the default behavior of dynamic binding when no
`lexical-binding` comment is present. With it set to `t` across the
board, various things break, and fixing those is a task for another day.
Since we enable global-company-mode, explicitly enabling it in the setup
for various major modes does nothing. But it does tie the code to
company mode, making it harder to try alternatives like corfu.
