Improve thread safety and performance in core systems

Refactors event, entity, and physics management to use thread-safe and lock-free data structures (Immutable collections, ConcurrentQueue, ConcurrentDictionary, Channel) for improved concurrency and performance. Replaces O(n) queue lookups with O(1) set/dictionary checks, ensures atomic updates for shared state, and optimizes queue draining and deferred action processing. Updates related code to use new APIs and patterns, and adds documentation for thread safety and workflow.

Barotrauma/BarotraumaShared/SharedSource/Events/EventSet.cs

@@ -3,6 +3,7 @@ using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
+using System.Threading;
 using System.Xml.Linq;
 
 namespace Barotrauma
@@ -60,47 +61,48 @@ namespace Barotrauma
             return null;
         }
 #endif
-
-        private static readonly Dictionary<Identifier, EventPrefab> AllEventPrefabs = new Dictionary<Identifier, EventPrefab>();
+        private static volatile ImmutableDictionary<Identifier, EventPrefab> _allEventPrefabs = 
+            ImmutableDictionary<Identifier, EventPrefab>.Empty;
 
         public static IEnumerable<EventPrefab> GetAllEventPrefabs()
         {
-            return AllEventPrefabs.Values;
+            return _allEventPrefabs.Values;
         }
 
         /// <summary>
         /// Finds all the event prefabs (both "normal prefabs" that exists by themselves, present in <see cref="EventPrefab.Prefabs"/>, and the ones that exists only inside child event sets),
-        /// and adds them to <see cref="AllEventPrefabs"/>.
+        /// and adds them to <see cref="_allEventPrefabs"/>.
         /// </summary>
         public static void RefreshAllEventPrefabs()
         {
-            AllEventPrefabs.Clear();
+            var builder = ImmutableDictionary.CreateBuilder<Identifier, EventPrefab>();
             foreach (var eventPrefab in EventPrefab.Prefabs)
             {
-                AllEventPrefabs.TryAdd(eventPrefab.Identifier, eventPrefab);
+                builder.TryAdd(eventPrefab.Identifier, eventPrefab);
             }
             foreach (var eventSet in Prefabs)
             {
-                AddChildEventPrefabs(eventSet);
+                AddChildEventPrefabs(eventSet, builder);
             }
+            Interlocked.Exchange(ref _allEventPrefabs, builder.ToImmutable());
         }
 
-        private static void AddChildEventPrefabs(EventSet set)
+        private static void AddChildEventPrefabs(EventSet set, ImmutableDictionary<Identifier, EventPrefab>.Builder builder)
         {
             foreach (var subEventPrefabs in set.EventPrefabs)
             {
                 foreach (var eventPrefab in subEventPrefabs.EventPrefabs)
                 {
-                    AllEventPrefabs.TryAdd(eventPrefab.Identifier, eventPrefab);
+                    builder.TryAdd(eventPrefab.Identifier, eventPrefab);
                 }
             }
 
-            foreach (var childSet in set.ChildSets) { AddChildEventPrefabs(childSet); }
+            foreach (var childSet in set.ChildSets) { AddChildEventPrefabs(childSet, builder); }
         }
 
         public static EventPrefab GetEventPrefab(Identifier identifier)
         {
-            return AllEventPrefabs.GetValueOrDefault(identifier);
+            return _allEventPrefabs.GetValueOrDefault(identifier);
         }
 
         /// <summary>