add dark mode support and light/dark toggle to the website #258
Description
Enhancement Description
the website only has a light mode and there's no way to switch to dark mode. i spend a lot of time reading through the docs and webapp pages late at night and the bright white background is genuinely painful after a while. most scientific tools and developer-facing sites have had dark mode support for years now, would be great to see it here too.
also the site doesn't respect the system-level dark mode preference (prefers-color-scheme: dark) — even if i have my whole OS set to dark mode, openms.de just loads in full bright white regardless.
To Reproduce
Steps to reproduce the behavior:
Set your OS/browser to dark mode
Visit https://openms.de/
Notice the site loads in full white/light mode with no toggle available
Check any sub-page — docs, webapp list, community pages — same issue across the board
