Minor usability improvements for the full details page

[maximecb]

This is technically two minor things so could be split into two issues, but they are both small 😅

We're trying to track down where the performance regression between these two runs comes from.
Before: https://speed.yjit.org/benchmarks/bench-2024-06-17-190814.html
After: https://speed.yjit.org/benchmarks/bench-2024-06-18-060815.html

I think it would be very useful to have a clear and direct link to the ruby/ruby commit on the full details page near the top, like on the front page. It would make identifying what happened a lot easier.

The second issue is that the full details page reports UTC times. This is impractical for everyone that doesn't live in or near that time zone. Ideally, times should be reported based on the local time zone, and the time zone, (GMT +/- N) should also be reported

[maximecb]

Thank you Randy! 🙂