Implement config-driven unlock groups so that multiple things can be unlocked at once (including buildings)

src/test/ShipyardTest.cpp

@@ -1,5 +1,7 @@
 #include "catch.hpp"
 
+#include <algorithm>
+
 #include "Building.h"
 #include "BuildingSystem.h"
 #include "BuildingType.h"
@@ -20,11 +22,24 @@ static GameConfig loadConfig()
     return ConfigLoader::loadFromDirectory(CONFIG_DIR);
 }
 
+// A ship starts unlocked iff no unlock group grants it (REQ-LOCK-EXPLICIT).
+static bool startsUnlocked(const GameConfig& cfg, const std::string& shipId)
+{
+    for (const UnlockGroupDef& group : cfg.unlocks.groups)
+    {
+        if (std::find(group.ships.begin(), group.ships.end(), shipId) != group.ships.end())
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
 static const ShipDef* findAvailableSchematic(const GameConfig& cfg)
 {
     for (const ShipDef& def : cfg.ships.ships)
     {
-        if (def.unlockAtStationLevel == -1 && !def.schematic.materials.empty())
+        if (startsUnlocked(cfg, def.id) && !def.schematic.materials.empty())
         {
             return &def;
         }