nvim_set_hl with just { bg = "none" } replaces the entire highlight
definition, wiping foreground and other attributes. This breaks
snacks.nvim GitHub integration (gh_pr/gh_issue pickers) which reads
fg from Normal/NormalFloat at require-time.
Use nvim_get_hl to fetch existing attributes first, remove only bg,
then set the highlight back.
See basecamp/omarchy#4844 for the companion migration for existing installs.