Type guard — check if a wire is planar (all edges lie in a common plane).
Strategy: try planar-only face construction first (fast path on OCCT — throws
for non-planar wires). If that succeeds, verify the surface type. If it
fails, fall back to general mode and check whether the resulting surface is
a plane. This handles kernel-specific differences in the planar flag.
Type guard — check if a wire is planar (all edges lie in a common plane). Strategy: try planar-only face construction first (fast path on OCCT — throws for non-planar wires). If that succeeds, verify the surface type. If it fails, fall back to general mode and check whether the resulting surface is a plane. This handles kernel-specific differences in the planar flag.