Add the package size NPM badge to the README

Author: kylecarbs

README.md

@@ -1,6 +1,6 @@
 # ghostty-web
 
-[![NPM Version](https://img.shields.io/npm/v/ghostty-web)](https://npmjs.com/package/ghostty-web) [![NPM Downloads](https://img.shields.io/npm/dw/ghostty-web)](https://npmjs.com/package/ghostty-web) [![license](https://img.shields.io/github/license/coder/ghostty-web)](./LICENSE)
+[![NPM Version](https://img.shields.io/npm/v/ghostty-web)](https://npmjs.com/package/ghostty-web) [![NPM Downloads](https://img.shields.io/npm/dw/ghostty-web)](https://npmjs.com/package/ghostty-web) [![npm bundle size](https://img.shields.io/bundlephobia/minzip/ghostty-web)](https://npmjs.com/package/ghostty-web) [![license](https://img.shields.io/github/license/coder/ghostty-web)](./LICENSE)
 
 [Ghostty](https://github.com/ghostty-org/ghostty) for the web with [xterm.js](https://github.com/xtermjs/xterm.js) API compatibility — giving you a proper VT100 implementation in the browser, not a JavaScript approximation of one.