junegunn/vim-plug ? reverse-engineered prompt

Build me a tiny Vim plugin manager like vim plg, something I can drop into my config as one file and use right away.

I want it to work in both Vim and Neovim, let me list plugins in a simple block, then install, update, clean, and review changes from inside the editor. It should support plugins from GitHub or any git URL, branches, tags, custom install folders, and simple post install commands. Please make startup stay fast, so load plugins only when I need them, and keep downloads small by cloning shallowly if possible.

If it helps, follow the current docs and behavior from vim plg closely, and make sure the default setup is easy enough for a regular user to understand without reading a lot.