Add hot potato (#14204)

Co-authored-by: AJCM <AJCM@tutanota.com>

Content.Client/HotPotato/HotPotatoSystem.cs

@@ -0,0 +1,26 @@
+using Content.Shared.HotPotato;
+using Robust.Shared.Random;
+using Robust.Shared.Timing;
+
+public sealed class HotPotatoSystem : SharedHotPotatoSystem
+{
+    [Dependency] private readonly IGameTiming _timing = default!;
+    [Dependency] private readonly IRobustRandom _random = default!;
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+
+        if (!_timing.IsFirstTimePredicted)
+            return;
+
+        var query = AllEntityQuery<ActiveHotPotatoComponent>();
+        while (query.MoveNext(out var uid, out var comp))
+        {
+            if (_timing.CurTime < comp.TargetTime)
+                continue;
+            comp.TargetTime = _timing.CurTime + TimeSpan.FromSeconds(comp.EffectCooldown);
+            Spawn("HotPotatoEffect", Transform(uid).MapPosition.Offset(_random.NextVector2(0.25f)));
+        }
+    }
+}