fix issue where shipyard did not produce anything

src/test/CombatSystemTest.cpp

@@ -52,6 +52,7 @@ TEST_CASE("CombatSystem: ship fires when cooldown=0 and target in range", "[comb
     BuildingSystem buildings(cfg, belts,
         [&nextBldId]() { return nextBldId++; },
         [](int){},
+        [](const std::string&, QVector2D) {},
         rng);
 
     // Spawn an enemy combat ship close to the player side.
@@ -112,6 +113,7 @@ TEST_CASE("CombatSystem: cooldown prevents firing before it expires", "[combat]"
     BuildingSystem buildings(cfg, belts,
         [&nextBldId]() { return nextBldId++; },
         [](int){},
+        [](const std::string&, QVector2D) {},
         rng);
 
     const EntityId enemyId  = ships.spawn(combatDef->id, 1, QVector2D(5.0f, 5.0f), true);
@@ -160,6 +162,7 @@ TEST_CASE("CombatSystem: no fire when target is out of range", "[combat]")
     BuildingSystem buildings(cfg, belts,
         [&nextBldId]() { return nextBldId++; },
         [](int){},
+        [](const std::string&, QVector2D) {},
         rng);
 
     const EntityId enemyId  = ships.spawn(combatDef->id, 1, QVector2D(0.0f,   0.0f), true);