Stratomission Lab Clean Page

This package keeps the current Stratomission Lab page layout and content, while cleaning implementation details:
- huge inline SVG replaced with external cleaned SVG asset
- animated hero mountain canvas moved to assets/js/header-mountains.js
- custom CSS moved to assets/css/stratomission.css
- --line CSS variable defined properly
- subtle graphical additions added to hero and research cards without changing the page structure

Open index.html in a browser.
