BeltTargets drops its own reach skip (TargetRegion.CanHold owns it) and an
empty-belt guard AsteroidBelt already makes unreachable. Tests add an
off-centre sun, whole-belt searches across the antipode, cost after time
passes, a late short step that re-keys nothing, and an entity search off the
origin.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>