Moves three mesh-aggregate info handlers (--info-zone-models-total,
--list-zone-meshes-detail, --info-mesh) out of main.cpp into a
new cli_mesh_info.{hpp,cpp} module. The first aggregates
WOM/WOB stats across a zone; the second tabulates per-mesh
metrics sorted by triangle count; the third dumps single-WOM
detail (bounds, version, batches, bones, animations, textures).
main.cpp shrinks by 285 lines (1,826 to 1,541). All three
preserve --json output for capacity-planning pipelines.
