Cargo selling fixes (#17876)

- Prevent selling dead mobs (getting used as easy corpse disposal).
- Fix a broadcast event being raised O(n) times instead of O(1)

Content.Server/Cargo/Systems/CargoSystem.cs

@@ -10,6 +10,7 @@ using Content.Shared.Access.Systems;
 using Content.Shared.Administration.Logs;
 using Content.Shared.Cargo;
 using Content.Shared.Containers.ItemSlots;
+using Content.Shared.Mobs.Components;
 using JetBrains.Annotations;
 using Robust.Server.GameObjects;
 using Robust.Shared.Configuration;
@@ -45,12 +46,18 @@ public sealed partial class CargoSystem : SharedCargoSystem
     [Dependency] private readonly UserInterfaceSystem _uiSystem = default!;
     [Dependency] private readonly MetaDataSystem _metaSystem = default!;
 
-    private ISawmill _sawmill = default!;
+    private EntityQuery<TransformComponent> _xformQuery;
+    private EntityQuery<CargoSellBlacklistComponent> _blacklistQuery;
+    private EntityQuery<MobStateComponent> _mobQuery;
 
     public override void Initialize()
     {
         base.Initialize();
-        _sawmill = Logger.GetSawmill("cargo");
+
+        _xformQuery = GetEntityQuery<TransformComponent>();
+        _blacklistQuery = GetEntityQuery<CargoSellBlacklistComponent>();
+        _mobQuery = GetEntityQuery<MobStateComponent>();
+
         InitializeConsole();
         InitializeShuttle();
         InitializeTelepad();
@@ -60,6 +67,7 @@ public sealed partial class CargoSystem : SharedCargoSystem
     public override void Shutdown()
     {
         base.Shutdown();
+        ShutdownShuttle();
         CleanupCargoShuttle();
     }