Merge remote-tracking branch 'upstream/stable' into ed-30-04-2025-upstream-sync

# Conflicts:
#	Content.Client/Parallax/ParallaxControl.cs
#	Content.Client/UserInterface/Systems/Storage/Controls/ItemGridPiece.cs
#	Content.IntegrationTests/Tests/PostMapInitTest.cs
#	Content.Server/Chat/Managers/ChatManager.cs
#	Content.Server/Fluids/EntitySystems/PuddleSystem.Evaporation.cs
#	Content.Server/Labels/Label/LabelSystem.cs
#	Content.Shared/Actions/SharedActionsSystem.cs
#	Content.Shared/Fluids/Components/EvaporationComponent.cs
#	Content.Shared/Labels/EntitySystems/SharedLabelSystem.cs
#	README.md
#	Resources/Prototypes/Entities/Mobs/Player/admin_ghost.yml
#	Resources/Prototypes/Maps/Pools/deathmatch.yml
#	Resources/Prototypes/Maps/arenas.yml

Content.Shared/Chemistry/Reaction/ChemicalReactionSystem.cs

@@ -15,6 +15,11 @@ namespace Content.Shared.Chemistry.Reaction
 {
     public sealed class ChemicalReactionSystem : EntitySystem
     {
+        /// <summary>
+        /// Foam reaction protoId.
+        /// </summary>
+        public static readonly ProtoId<ReactionPrototype> FoamReaction = "Foam";
+
         /// <summary>
         ///     The maximum number of reactions that may occur when a solution is changed.
         /// </summary>