migrate every factory query off BuildingSystem onto the free functions

src/test/WaveSystemTest.cpp

@@ -1,4 +1,5 @@
 #include "catch.hpp"
+#include "FactoryQueries.h"
 
 #include <random>
 
@@ -100,7 +101,7 @@ TEST_CASE("WaveSystem: Simulation pre-places HQ + 2 player + 2 enemy stations",
 
     // HQ is still a Building (for belt integration).
     int hqCount = 0;
-    for (const Building& b : sim.getBuildings().getAllBuildings())
+    for (const Building& b : getAllBuildings(sim.getFactoryState()))
     {
         if (b.type == BuildingType::Hq) { ++hqCount; }
     }
@@ -143,7 +144,7 @@ TEST_CASE("WaveSystem: HQ anchor is at asteroid right edge", "[wave]")
 {
     const Simulation sim(loadTestConfig(), 42);
 
-    for (const Building& b : sim.getBuildings().getAllBuildings())
+    for (const Building& b : getAllBuildings(sim.getFactoryState()))
     {
         if (b.type != BuildingType::Hq) { continue; }
         // Rightmost body cell must be at x = -1 (asteroid right edge).