Add building status light

src/ui/VisualsConfig.h

@@ -60,6 +60,17 @@ struct ToastVisuals
     int    fontSize;
 };
 
+// Fill colors for the building status light (REQ-UI-STATUS-LIGHT), plus its
+// constant outline color.
+struct StatusLightVisuals
+{
+    QColor grey;    // no recipe/schematic selected
+    QColor green;   // producing
+    QColor red;     // idle, input missing (or Salvage Bay empty)
+    QColor yellow;  // idle, output buffer full
+    QColor outline;
+};
+
 struct VisualsConfig
 {
     TileVisuals asteroid;
@@ -69,7 +80,8 @@ struct VisualsConfig
     std::map<std::string,  ItemVisuals>     items;
     std::map<std::string,  ShipVisuals>     ships;
 
-    BeamVisuals    beams;
-    OverlayVisuals overlays;
-    ToastVisuals   toast;
+    BeamVisuals        beams;
+    OverlayVisuals     overlays;
+    ToastVisuals       toast;
+    StatusLightVisuals statusLight;
 };