docs(v3.5.0): update README for integrated mg_dotfiles and security improvements

- Integrated mg_dotfiles as regular directory (not submodule)
- Added .zshrc.local.example template for local configs without secrets
- Added mg_dotfiles/zsh/.zshrc.local to .gitignore to protect API keys
- Updated README to reflect mg_dotfiles integration and new structure
- Added nvim configuration directory with LazyVim setup

mg_dotfiles/nvim/lua/plugins/multi-line.lua

@@ -0,0 +1,10 @@
+-- This file contains the configuration for the vim-multiple-cursors plugin in Neovim.
+
+return {
+  {
+    -- Plugin: vim-multiple-cursors
+    -- URL: https://github.com/terryma/vim-multiple-cursors
+    -- Description: A Vim plugin that allows multiple cursors for simultaneous editing.
+    "terryma/vim-multiple-cursors",
+  },
+}