read tunnel length from different config and fix tests

src/lib/config/BuildingsConfig.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <optional>
 #include <string>
 #include <vector>
 
@@ -19,7 +18,6 @@ struct BuildingDef
     // Stored as raw strings here; parsing into per-cell tiles + output ports
     // happens when buildings are placed, not at load time.
     std::vector<std::string> surfaceMask;
-    std::optional<int> tunnelMaxDistance;
 };
 
 struct BuildingsConfig