WIP Make collections thread-safe and add safe iteration

Replaced static lists and dictionaries with thread-safe ConcurrentDictionary or ThreadLocal collections for various item components and systems. Updated all relevant code to use snapshots (ToArray, ToList) for safe iteration, and added helper methods for marking and clearing changed connections. These changes improve thread safety and prevent potential concurrency issues in multi-threaded scenarios.

Barotrauma/BarotraumaShared/SharedSource/Items/Components/Holdable/Holdable.cs

@@ -9,6 +9,7 @@ using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
+using System.Threading;
 using System.Xml.Linq;
 
 namespace Barotrauma.Items.Components
@@ -616,12 +617,13 @@ namespace Barotrauma.Items.Components
             return CanBeAttached(user, out _);
         }
 
-        private static List<Item> tempOverlappingItems = new List<Item>();
+        private static readonly ThreadLocal<List<Item>> tempOverlappingItems = new ThreadLocal<List<Item>>(() => new List<Item>());
 
         private bool CanBeAttached(Character user, out IEnumerable<Item> overlappingItems)
         {
-            tempOverlappingItems.Clear();
-            overlappingItems = tempOverlappingItems;
+            var overlapping = tempOverlappingItems.Value;
+            overlapping.Clear();
+            overlappingItems = overlapping;
             if (!attachable || !Reattachable) { return false; }
 
             //can be attached anywhere in sub editor
@@ -664,9 +666,9 @@ namespace Barotrauma.Items.Components
                     }                        
                     if (attachPos.X + size.X < worldRect.X || attachPos.X - size.X > worldRect.Right) { continue; }
                     if (attachPos.Y - size.Y > worldRect.Y || attachPos.Y + size.Y < worldRect.Y - worldRect.Height) { continue; }
-                    tempOverlappingItems.Add(otherItem);
+                    overlapping.Add(otherItem);
                 }
-                if (tempOverlappingItems.Any()) { return false; }
+                if (overlapping.Any()) { return false; }
             }
 
             //can be attached anywhere inside hulls