Fix silently interpreting zero time range as latest-at query

[Wumpf]

What

• Fixes Zero-lengthed visible time ranges shouldn't silently fall back to latest-at #6135

plus (and that's the bigger part of this PR) refactor time range handling to remove old VisibleHistory rust types.
Commit by commit review recommended.

Still need to fix the ui to better communicate when latest-at is used.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
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[github-actions]

Deployed docs

Commit	Link
fd3f006	https://landing-rfoiglwge-rerun.vercel.app/docs

[Wumpf]

looks like I broke something. arkitscenes doesn't show its mesh anymore

[Wumpf]

already broken on main
#6175