enabled coloured underlines for spelling diagnostics

lua/paper-tonic-modern/groups/treesitter.lua

@@ -292,6 +292,6 @@ return {
   ['@none'] = {},
   ['@conceal'] = { fg = c.fg_weaker },
   
-  ['@spell'] = {},
-  ['@nospell'] = {},
+  -- @spell and @nospell should not define any styling
+  -- This allows vim.wo.spell to control spell highlighting via SpellBad/SpellCap/etc
 }