Clown shoes make you waddle, as God intended (#26338)

* Clown shoes make you waddle, as God intended

* OOPS

* Toned down, client system name fix

* Tidy namespacing for @deltanedas

* Refactor to handle prediction better, etc.

* Resolve PR comments.

Content.Shared/Movement/Components/WaddleAnimationComponent.cs

@@ -0,0 +1,72 @@
+using System.Numerics;
+
+namespace Content.Shared.Movement.Components;
+
+/// <summary>
+/// Declares that an entity has started to waddle like a duck/clown.
+/// </summary>
+/// <param name="Entity">The newly be-waddled.</param>
+[ByRefEvent]
+public record struct StartedWaddlingEvent(EntityUid Entity)
+{
+    public EntityUid Entity = Entity;
+}
+
+/// <summary>
+/// Declares that an entity has stopped waddling like a duck/clown.
+/// </summary>
+/// <param name="Entity">The former waddle-er.</param>
+[ByRefEvent]
+public record struct StoppedWaddlingEvent(EntityUid Entity)
+{
+    public EntityUid Entity = Entity;
+}
+
+/// <summary>
+/// Defines something as having a waddle animation when it moves.
+/// </summary>
+[RegisterComponent]
+public sealed partial class WaddleAnimationComponent : Component
+{
+    /// <summary>
+    /// What's the name of this animation? Make sure it's unique so it can play along side other animations.
+    /// This prevents someone accidentally causing two identical waddling effects to play on someone at the same time.
+    /// </summary>
+    [DataField]
+    public string KeyName = "Waddle";
+
+    ///<summary>
+    /// How high should they hop during the waddle? Higher hop = more energy.
+    /// </summary>
+    [DataField]
+    public Vector2 HopIntensity = new(0, 0.25f);
+
+    /// <summary>
+    /// How far should they rock backward and forward during the waddle?
+    /// Each step will alternate between this being a positive and negative rotation. More rock = more scary.
+    /// </summary>
+    [DataField]
+    public float TumbleIntensity = 20.0f;
+
+    /// <summary>
+    /// How long should a complete step take? Less time = more chaos.
+    /// </summary>
+    [DataField]
+    public float AnimationLength = 0.66f;
+
+    /// <summary>
+    /// How much shorter should the animation be when running?
+    /// </summary>
+    [DataField]
+    public float RunAnimationLengthMultiplier = 0.568f;
+
+    /// <summary>
+    /// Stores which step we made last, so if someone cancels out of the animation mid-step then restarts it looks more natural.
+    /// </summary>
+    public bool LastStep;
+
+    /// <summary>
+    /// Stores if we're currently waddling so we can start/stop as appropriate and can tell other systems our state.
+    /// </summary>
+    public bool IsCurrentlyWaddling;
+}