Fix darkmode (again?)

[noah-severyn]

I'm not quite sure if this solves the issue, but a long chat with Claude suggests we're missing this line: e88f13f

This was the root cause: Without this setting, Bootstrap 5.3+ doesn't generate the CSS rules that update CSS variables like --bs-warning-bg-subtle when data-bs-theme="dark" is set.

Some troubleshooting points:

• The strange thing is everything works perfectly fine when deployed to localhost, which makes this kinda hard to test.
• The data-bs-theme attribute does correctly toggle on the deployed site
• I've also confirmed that both darkmode-init.js and darkmode.js in the published site are up to date, so it doesn't seem to be a caching problem with those files.