nvim: Add undotree plugin

Lua implementation of the undo tree plugin, mapped to be
reachable with <leader>su (for show undo).

nvim/.config/nvim/lazy-lock.json

@@ -66,6 +66,7 @@
   "telescope-fzf-native.nvim": { "branch": "main", "commit": "9bc8237565ded606e6c366a71c64c0af25cd7a50" },
   "telescope.nvim": { "branch": "master", "commit": "776b509f80dd49d8205b9b0d94485568236d1192" },
   "twilight.nvim": { "branch": "main", "commit": "8bb7fa7b918baab1ca81b977102ddb54afa63512" },
+  "undotree": { "branch": "main", "commit": "2685ce282702ab0b79c65916f352db2265b245dd" },
   "vifm.vim": { "branch": "master", "commit": "a8130c37d144b51d84bee19f0532abcd3583383f" },
   "vim-criticmarkup": { "branch": "master", "commit": "d15dc134eb177a170c79f6377f81eb02a9d20b02" },
   "vim-easy-align": { "branch": "master", "commit": "0db4ea6132110631ec678a99a82aa49a0686ae65" },

nvim/.config/nvim/lua/core/mappings.lua

@@ -284,3 +284,10 @@ map(
 	'<cmd>lua require("colorizer").attach_to_buffer(0, {mode = "background"} )<cr>',
 	{ silent = true, desc = "colorize background" }
 )
+
+-- PLUGIN: undotree
+if is_available("undotree") then
+	map("n", "<leader>su", function()
+		require("undotree").toggle()
+	end, { silent = true, desc = "toggle undotree" })
+end

nvim/.config/nvim/lua/plugins/ui.lua

@@ -50,4 +50,11 @@ return {
 		end,
 		event = "VeryLazy",
 	},
+	{
+		"jiaoshijie/undotree",
+		dependencies = {
+			"nvim-lua/plenary.nvim",
+		},
+		config = true,		event = "VeryLazy",
+	},
 }