added modularity: separated files for keymaps, telescope. added undotree plugin. small features like relative line numbers.

lua/custom/plugins/undotree.lua

@@ -0,0 +1,14 @@
+-- lua/custom/plugins/undotree.lua
+return {
+  'mbbill/undotree',
+  keys = {
+    { '<leader>u', vim.cmd.UndotreeToggle, desc = 'Toggle UndoTree' },
+  },
+  config = function()
+    -- Optional settings
+    vim.g.undotree_WindowLayout = 2 -- vertical split
+    vim.g.undotree_SplitWidth = 30 -- width of undo tree window
+    vim.g.undotree_SetFocusWhenToggle = 1
+    vim.g.undotree_EnableDiff = 1
+  end,
+}