Never rotate tunnels in place

src/lib/sim/BuildingSystem.cpp

@@ -1492,6 +1492,13 @@ bool BuildingSystem::isTileOccupied(QPoint tile) const
 std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
     BuildingType type, QPoint anchor, Rotation rot) const
 {
+    // Tunnel Entries and Tunnel Exits cannot be rotated in place; re-orienting a
+    // tunnel requires demolishing and re-placing it (REQ-BLD-ROTATE-IN-PLACE).
+    if (type == BuildingType::TunnelEntry || type == BuildingType::TunnelExit)
+    {
+        return std::nullopt;
+    }
+
     const BuildingDef* def = findBuildingDef(type);
     if (!def) { return std::nullopt; }