Modernize deprecated Neovim APIs

vim.loop -> vim.uv and vim.highlight.range -> vim.hl.range. Also drop the
completeopt comment referring to nvim-cmp, which blink.cmp replaced.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lua/config/options.lua

@@ -10,7 +10,6 @@ else
   vim.opt.guifont = "Berkeley Mono Variable:h13"
 end
 
--- idk if it does anything cause I have to set it in the nvim-cmp settings too
 vim.opt.completeopt = "menu,menuone,noinsert,noselect"
 
 -- Window decorations