feat: add border config to neo-tree

lua/plugins/neo-tree.lua

@@ -1,3 +1,6 @@
+
+ui = require 'config.ui'
+
 return {
     "nvim-neo-tree/neo-tree.nvim",
     lazy = false,
@@ -9,6 +12,7 @@ return {
     },
     cmd = "Neotree",
     opts = {
+        popup_border_style = ui.border,
         source_selector = {
             winbar = true,
             statusline = false,