Z-conformance sentinel for issue #51's bug class. Sweeps 10
representative landblocks x 100 sample points (uniform random in
local 0..192 with fixed seed 42). For each point: compute meshTriZ
via barycentric interpolation in the matching triangle of the
LandblockMesh.Build output; compute physicsZ via
TerrainSurface.SampleZFromHeightmap; assert |delta| < 0.001m.
Catches any silent formula or vertex-layout drift between the
visual and physics paths. Skips gracefully if ACDREAM_DAT_DIR
isn't set (CI without dat data).
Local run with dat data: 10/10 landblocks loaded, 1000 samples,
max |delta| = 0.0305 mm (worst case: Direlands 0xC040).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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