Allow creating blueprints from construction sites

src/lib/sim/BuildingConfig.h

@@ -4,6 +4,7 @@
 #include <string>
 #include <vector>
 
+#include "Blueprint.h"
 #include "BuildingId.h"
 #include "BuildingType.h"
 #include "ItemType.h"
@@ -38,3 +39,16 @@ struct BuildingConfig
 // by id, handling operational buildings and sites alike. Returns std::nullopt if
 // no such building or site exists.
 std::optional<BuildingConfig> readBuildingConfig(const Simulation& sim, BuildingId id);
+
+// Captures a blueprint from a selection of building / construction-site ids, keeping
+// only player-placeable buildings and recording each one's type, rotation, offset
+// from the selection's bounding-box center, and configuration. Operational buildings
+// and construction sites are treated identically (REQ-UI-BLUEPRINT-CREATE,
+// REQ-UI-BLUEPRINT-STORAGE). The returned blueprint is unnamed.
+Blueprint captureBlueprintFromSelection(const Simulation&              sim,
+                                        const std::vector<BuildingId>& selectedIds);
+
+// True if any selected id refers to a player-placeable building or construction site
+// (the enable condition for the Create Blueprint button, REQ-UI-BLUEPRINT-CREATE).
+bool selectionHasPlaceableBuilding(const Simulation&              sim,
+                                   const std::vector<BuildingId>& selectedIds);