adopt neovim 0.12 native editing features

lua/settings.lua

@@ -65,14 +65,8 @@ vim.opt.tabline = '%!v:lua.require("utils").custom_tabline()'
 vim.opt.showtabline = 1 -- Show tabline only when there are 2+ tabs
 
 -- Phase 3.2: non-plugin settings (legacy values where specified)
--- Completion UI for nvim-cmp
-vim.opt.completeopt = { "menu", "menuone", "noselect" }
-
--- Built-in completion popup style (for Ctrl-X Ctrl-N/F completions)
--- Use floating window with border for native completion
+-- Native completion popup style
 vim.opt.pumblend = 0 -- No transparency
--- Note: Native completion (pumvisible) doesn't support custom borders like LSP floats
--- The Pmenu* highlight groups control its appearance
 
 -- Spelling
 vim.opt.spell = true