add basic types and fix cmake

src/lib/config/BuildingsConfig.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "BuildingType.h"
+
+// A single entry from buildings.toml [[building]].
+struct BuildingDef
+{
+    std::string id;                      // Raw id string from TOML, e.g. "miner".
+    BuildingType type;                   // Parsed from id at load time.
+    int cost;                            // REQ-BLD-COST
+    bool playerPlaceable;                // Shown in the build menu if true.
+    double constructionTimeSeconds;      // REQ-BLD-QUEUE
+
+    // Rows of the surface_mask (REQ-BLD requirements, "Surface Mask Format").
+    // 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;
+};
+
+struct BuildingsConfig
+{
+    std::vector<BuildingDef> buildings;
+};