refactor(nvim): use undercurl for commit msg warning len

dots/.config/nvim/lua/plugins/configs/kanagawa.lua

@@ -222,6 +222,17 @@ return {
                 { "NotificationWarning", { link = "NvimNotifyWarn" } },
                 { "NotificationError", { link = "NvimNotifyError" } },
 
+                {
+                    "@comment.warning.gitcommit",
+                    {
+                        undercurl = true,
+                        sp = function()
+                            return get_hl("@comment.warning")().bg
+                        end,
+                        nocombine = true,
+                    },
+                },
+
                 -- LSP hls
                 { "@lsp.typemod.variable.global", { fg = colors.lightBlue } },