make selection box sub-tile aware

src/lib/sim/FactoryQueries.h

@@ -3,6 +3,7 @@
 #include <vector>
 
 #include <QPoint>
+#include <QRectF>
 #include <QVector2D>
 
 #include "Building.h"
@@ -71,11 +72,12 @@ std::optional<BeltSystem::SplitterInfo> getSiteSplitterInfo(const FactoryState&
                                                             const GameConfig& config,
                                                             BuildingId id);
 
-// Ids of all buildings and construction sites whose footprint intersects the tile
-// box spanned by the two (unordered) corner tiles (REQ-UI-MULTI-SELECT,
-// REQ-BLD-DECONSTRUCT-BOX).
+// Ids of all buildings and construction sites the selection box covers — those with
+// a body cell the box overlaps, per boxCoversTile (REQ-UI-MULTI-SELECT,
+// REQ-BLD-DECONSTRUCT-BOX). `worldBox` is in world coordinates and normalized; it is
+// not snapped to tiles.
 std::vector<BuildingId> buildingsInBox(const FactoryState& state,
-                                       QPoint cornerA, QPoint cornerB);
+                                       const QRectF& worldBox);
 
 // Every tunnel entry and exit, built or still a construction site, indexed by its
 // single-cell tile. Shared by the placement preview and the selection highlight.