depend on factory data instead of BuildingSystem in the AI path

Ten queries that read nothing but FactoryState become free functions in
FactoryQueries.h; the BuildingSystem methods stay as one-line forwards, so no
existing caller moves yet.

That lets the AI path drop its dependency on the system entirely. AiSystem,
SalvagerSystem, DeliverScrapEvaluator and DeliverScrapExecutor took a
BuildingSystem& purely to call findBuilding, findNearestBuilding and
deliverScrapToSalvageBay — all three are state-pure — so they now take
FactoryState& and say what they actually read. Four forward declarations of
BuildingSystem go with them.

No facade: the queries are plain free functions over the data. A facade was
considered to spare the ~180 UI call sites, but the AI needed only the data and
would have been given GameConfig it has no use for.

isProductionBuildingType moves to BuildingType.h beside isAutoRecipeBuildingType
and isBeltSubsystemType rather than being copied into the new file.

Verified with a golden-checksum capture before and after — all four sample ticks
identical.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YHcUerKAZKWNvSKJxYKbnG

src/lib/core/BuildingType.cpp

@@ -52,3 +52,18 @@ bool isBeltSubsystemType(BuildingType type)
         || type == BuildingType::TunnelEntry
         || type == BuildingType::TunnelExit;
 }
+
+bool isProductionBuildingType(BuildingType type)
+{
+    switch (type)
+    {
+    case BuildingType::Miner:
+    case BuildingType::Smelter:
+    case BuildingType::Assembler:
+    case BuildingType::ReprocessingPlant:
+    case BuildingType::Shipyard:
+        return true;
+    default:
+        return false;
+    }
+}

src/lib/core/BuildingType.h

@@ -35,6 +35,10 @@ std::string buildingTypeId(BuildingType type);
 // they receive, matching against every recipe of their building type.
 bool isAutoRecipeBuildingType(BuildingType type);
 
+// Buildings that run a production cycle: Miner, Smelter, Assembler, Reprocessing
+// Plant and Shipyard (REQ-UI-DEBUG-OVERLAY counts these).
+bool isProductionBuildingType(BuildingType type);
+
 // Belts, splitters, and tunnel ends keep their runtime data in the belt subsystem
 // rather than in the Building instance, so placing/removing them must register or
 // unregister a tile with BeltSystem.