Add deconstruction queue

src/lib/sim/Building.h

@@ -129,5 +129,10 @@ struct Building
 
     // Module layout for shipyards (REQ-MOD-LAYOUT).
     std::optional<ShipLayoutConfig> shipLayout;
+
+    // True while this building sits in the deconstruction queue (REQ-BLD-DECON-QUEUE).
+    // A queued building stops operating immediately (all tick loops skip it) but keeps
+    // occupying its tiles until its deconstruction completes.
+    bool queuedForDeconstruction = false;
 };