See a mentor's actual local time, not a timezone name

Finding a mentor in a workable timezone used to mean decoding names like "W. Central Africa Standard Time" yourself. Mentor profiles now show the thing you actually want to know: what time it is for them right now, and how far ahead or behind you they are -- for example, "4:30 PM for them right now, 6 hours ahead of you."

Under the hood, every timezone a member can pick is now backed by a real timezone database entry with correct daylight-saving rules, and an automated check keeps it that way. This is also the groundwork for smarter mentor matching by working-hours overlap, which is on the roadmap.