Add GeoBounds and type the geography doors with Latitude and Longitude

[LahaLuhem]

Closes #65.

GeoBounds is a GeoJSON bbox where west > east is legal rather than refused, that being how
RFC 7946 §5.2 spells a box across the antimeridian. crossesAntimeridian reports the crossing and
contains honours it, so the case that goes wrong near ±180 is a type-level fact instead of
something every caller re-derives. Geohash.bounds returns one, so a geohash can hand back the cell
it names rather than only a point inside it.

Breaking, minted_geography major. GeoCoordinate.from took two doubles and returned a
ParseOutcome; it now takes a Latitude and a Longitude and cannot fail. tryFrom is the
raw-number door, widened to num. The range moved into the types, so it is prevented at the
assembly doors and only parse still diagnoses it, text being where unchecked input arrives.

The edges are numbers rather than two GeoCoordinate corners deliberately: a coordinate folds
-180 onto +180, right for a point and wrong for an edge, and folded corners would turn
-180,-90,180,90 into a meridian line. Reasoning in APPENDIX.md#geo-bounds-value-type.

Worth settling before this releases: #70 asks whether the getters get typed too. A probe says
implements double keeps the range, swap and generic guarantees while removing the arithmetic tax,
so if it lands it can ride this same major rather than forcing a second one.