add basic types and fix cmake

src/lib/config/GameConfig.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "WorldConfig.h"
+#include "BuildingsConfig.h"
+#include "RecipesConfig.h"
+#include "ShipsConfig.h"
+#include "StationsConfig.h"
+
+// Aggregate of all five simulation config files, loaded once at startup and
+// immutable for the rest of the game. See architecture.md "Config Loading".
+struct GameConfig
+{
+    WorldConfig world;
+    BuildingsConfig buildings;
+    RecipesConfig recipes;
+    ShipsConfig ships;
+    StationsConfig stations;
+};