Quick Connect UX Improvement - Fix major delay

[grimyfishtank]

Problem

The Quick Connect page (/quick-connect/) has a noticeable delay before the network selection buttons become interactive. Users can see the buttons, but clicking them does nothing until the page fully loads several seconds later.

Root Cause

Two external scripts in extra_javascript are loaded as synchronous (blocking) <script> tags:

1. polyfill.io — This domain was compromised in a supply chain attack in 2024. The domain is now unreliable and causes the browser to hang for 30+ seconds waiting for a timeout before DOMContentLoaded fires.
2. MathJax CDN — A ~1MB library loaded synchronously on every page, but only used on a single page (Swapping-sol-to-2z.md).

Since the connection wizard attaches its click handlers on DOMContentLoaded, these blocking scripts prevent all button interactivity until they finish loading (or timeout).

Fix

• Remove polyfill.io — compromised and unnecessary (all modern browsers support ES6 natively)
• Load MathJax with async — prevents it from blocking the DOM parser and page interactivity