Moves all 4 GLB introspection handlers (--validate-glb /
--info-glb shared, --info-glb-tree, --info-glb-bytes,
--check-glb-bounds) out of main.cpp into a new
cli_glb_inspect.{hpp,cpp} module. GLB is our open replacement
for proprietary M2/WMO bake outputs, so these belong with the
other open-format tooling.
main.cpp shrinks by 657 lines (10,121 to 9,464). Every
handler preserves its --json output mode for machine-readable
reports.
