(Low Priority) Construction Beam obstructing

Add a game rule that makes builder account for landscape, obstructing its construction (repair/reclaim/capture) beam/spray
Should work same as Beam weapon
When ordered, builder will position itself where it can build from
Obstruct _only by landscape_, not units

Start by finding the existing Beam weapon behavior and the builder handling for construction, repair, reclaim, and capture orders. Compare how landscape obstruction and positioning are handled, then verify that only landscape blocks the beam and that the builder positions itself to build when ordered.

Written by the indexing model from the issue text.