Update nvim config: split plugins, update README

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nvim/lua/plugins/todo-comments.lua

@@ -0,0 +1,14 @@
+return {
+  {
+    "folke/todo-comments.nvim",
+    event = "VeryLazy",
+    dependencies = { "nvim-lua/plenary.nvim" },
+    opts = {},
+    keys = {
+      { "]t", function() require("todo-comments").jump_next() end, desc = "Next Todo Comment" },
+      { "[t", function() require("todo-comments").jump_prev() end, desc = "Prev Todo Comment" },
+      { "<leader>xt", "<cmd>Trouble todo<cr>", desc = "Todo (Trouble)" },
+      { "<leader>st", "<cmd>TodoTelescope<cr>", desc = "Todo" },
+    },
+  },
+}