Cherrypicks 5 (#440)

* Chances of triggering effects (#27056)

* electrocution

* slippery

* flashibg

* Update SlipperyComponent.cs

* Update SlipperySystem.cs

* Flash buff (#25730)

* flash buff

* oops!

* bool

* 3 -> 1.5 seconds

* okay fix

* sluth

* Flash overlay rework and bugfixes (#27369)

* fix mapping door access (#27784)

Co-authored-by: deltanedas <@deltanedas:kde.org>

* - fix: Errors.

* - fix: Incorporeal.

---------

Co-authored-by: Ed <96445749+TheShuEd@users.noreply.github.com>
Co-authored-by: Nemanja <98561806+EmoGarbage404@users.noreply.github.com>
Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>
Co-authored-by: deltanedas <39013340+deltanedas@users.noreply.github.com>

Content.Shared/Flash/Components/FlashComponent.cs

@@ -1,6 +1,6 @@
-using Content.Shared.Flash;
 using Robust.Shared.Audio;
 using Robust.Shared.GameStates;
+using Robust.Shared.Serialization;
 
 namespace Content.Shared.Flash.Components
 {
@@ -12,6 +12,13 @@ namespace Content.Shared.Flash.Components
         [ViewVariables(VVAccess.ReadWrite)]
         public int FlashDuration { get; set; } = 5000;
 
+        /// <summary>
+        /// How long a target is stunned when a melee flash is used.
+        /// If null, melee flashes will not stun at all
+        /// </summary>
+        [DataField]
+        public TimeSpan? MeleeStunDuration = TimeSpan.FromSeconds(1.5);
+
         [DataField("range")]
         [ViewVariables(VVAccess.ReadWrite)]
         public float Range { get; set; } = 7f;
@@ -32,5 +39,17 @@ namespace Content.Shared.Flash.Components
         };
 
         public bool Flashing;
+
+        [DataField]
+        public float Probability = 1f;
+    }
+
+    [Serializable, NetSerializable]
+    public enum FlashVisuals : byte
+    {
+        BaseLayer,
+        LightLayer,
+        Burnt,
+        Flashing,
     }
 }