delete the unused getAllBeltTiles and BeltTileInfo

Nothing in lib, ui, balancing or the tests calls it — the only references were
its own declaration and definition.

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

src/lib/sim/BuildingSystem.cpp

@@ -1263,38 +1263,6 @@ void BuildingSystem::forEachIncomingItem(
 
 
 
-std::vector<BuildingSystem::BeltTileInfo> BuildingSystem::getAllBeltTiles() const
-{
-    std::vector<BeltTileInfo> result;
-    for (const Building& b : m_state.buildings)
-    {
-        if (b.type != BuildingType::Belt && b.type != BuildingType::Splitter)
-        {
-            continue;
-        }
-        BeltTileInfo info;
-        info.buildingId = b.id;
-        info.tile = b.bodyCells.empty() ? b.anchor : b.bodyCells[0];
-        info.type = b.type;
-        if (!b.outputPorts.empty())
-        {
-            info.directionA = b.outputPorts[0].direction;
-            info.directionB = b.outputPorts[0].direction;
-        }
-        else
-        {
-            info.directionA = b.rotation;
-            info.directionB = b.rotation;
-        }
-        if (b.type == BuildingType::Splitter && b.outputPorts.size() >= 2)
-        {
-            info.directionB = b.outputPorts[1].direction;
-        }
-        result.push_back(info);
-    }
-    return result;
-}
-
 std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
     BuildingType type, QPoint anchor, Rotation rot) const
 {