new theme: Manticore Sphinx

[manticore-projects]

https://github.com/manticore-projects/manticore-sphinx-theme

• Configurable using SASS and CSS variables.
• Bulma-based — uses Bulma's SASS architecture for consistent, modern styling.
• No NPM required — compiles with Python libsass or standalone dart-sass.
• Landing page w/ cards and smooth marquee.

Let me know how you like it, suggestions and improvements are most welcome.
Cheers!