v0.6.0 — capability parity (buildable gaps vs ODM / Metashape / RealityCapture)

v0.6.0 — capability parity (buildable gaps vs ODM / Metashape / RealityCapture)

Closes the buildable capability gaps to the established tools: vector contour
lines (GPKG + DXF), OGC 3D Tiles export (Obj2Tiles), ML multi-class point
classification (OpenPointClass), multi-epoch change detection (ICP
co-registration + DEM-of-difference + M3C2), and orthomosaic radiometric
colour-balance finishing. Plus engine hardening: the dead OpenSfM sparse path
removed and InterfaceCOLMAP resolved through a fail-loud alias lookup, and the
Docker images slimmed to a multi-stage builder->runtime layout (CPU 3.24->1.65 GB,
runtime exercise gate; GPU mirrored in lock-step).