show threat rate in debug output

src/lib/sim/BuildingSystem.h

@@ -79,6 +79,14 @@ public:
     const ConstructionSite*   findSite(BuildingId id)      const;
     std::vector<Building>     allBuildings()             const;
     std::vector<ConstructionSite> allSites()             const;
+
+    // REQ-UI-DEBUG-OVERLAY "Max Factory Production": count of completed
+    // (operational) Miner/Smelter/Assembler/ReprocessingPlant/Shipyard buildings.
+    int productionBuildingCount() const;
+
+    // REQ-UI-DEBUG-OVERLAY "Current Factory Production": subset of the above
+    // that currently has an active production cycle.
+    int activeProductionBuildingCount() const;
     std::vector<BeltTileInfo> allBeltTiles()             const;
     bool                      isTileOccupied(QPoint tile) const;