cleanup(geo): retire stale Spherical_lonlat workaround; re-enable GEODSTBOX ZT area test

[estebanzimanyi]

Summary

src/geo/stbox_functions.cpp carries three helpers — Spherical_lonlat_rect_area_m2, Geodetic_stbox_footprint_area, Stbox_geodetic_xy_copy — that workaround MEOS-1.3 bugs that the pinned MEOS-1.4 integration tip does not have:

Helper	MEOS-1.4 status
Spherical_lonlat_rect_area_m2 / Geodetic_stbox_footprint_area	stbox_area(GEODSTBOX ZT(((1,2,3),(4,5,6)),[2000-01-01,2000-01-02])) returns 110593375170.3 cleanly — no SIGSEGV on the PolyhedralSurface path
Stbox_geodetic_xy_copy	stbox_to_geo projects 3D geodetic boxes to a 2D POLYGON with Z=0 internally
(geog_in WKT fall-through)	fixed upstream in MobilityDB PR #1090 (closes #1089)

This PR

• removes the three workaround helpers
• replaces Stbox_area with a direct stbox_area call (the dead == DBL_MAX error sentinel becomes < 0, matching MEOS's documented -1.0 on error)
• simplifies Stbox_expand_space to call stbox_to_geo directly
• re-enables the GEODSTBOX ZT area test that was commented out, with MEOS's value (110593375170.3) as the expected output
• adds GEODSTBOX X and GEODSTBOX Z area tests for coverage

Verification

Direct probes against the pinned MEOS-1.4 (integration/meos-1.4-bump):

GEODSTBOX ZT(((1.0,2.0,3.0),(4.0,5.0,6.0)),[2000-01-01,2000-01-02])
    stbox_area(spheroid=true)  = 110593375170.3
    stbox_area(spheroid=false) = 111083945187.3
GEODSTBOX X((1.0,2.0),(3.0,4.0))
    stbox_area(spheroid=true)  = 49173168695.2
GEODSTBOX Z((1.0,2.0,3.0),(4.0,5.0,6.0))
    stbox_area(spheroid=true)  = 110593375170.3

No SIGSEGV on any path.

Dependency

Requires the MEOS-1.4 vcpkg pin from #164 (or any pin that includes #1090). This PR stacks on #164.

Files changed

src/geo/stbox_functions.cpp | 51 ++++++-----------------------------------
test/sql/stbox.test         | 19 +++++++++++++-----
2 files changed, 18 insertions(+), 51 deletions(-)