ECS handheld lights (#5864)

Content.Client/Light/HandheldLightSystem.cs

@@ -0,0 +1,23 @@
+using Content.Client.Light.Components;
+using Content.Shared.Light.Component;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameStates;
+
+namespace Content.Client.Light;
+
+public sealed class HandheldLightSystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<HandheldLightComponent, ComponentHandleState>(OnHandleState);
+    }
+
+    private void OnHandleState(EntityUid uid, HandheldLightComponent component, ref ComponentHandleState args)
+    {
+        if (args.Current is not SharedHandheldLightComponent.HandheldLightComponentState state)
+            return;
+
+        component.Level = state.Charge;
+    }
+}