fix(anim): Phase L.1c clamp approach velocity to prevent overshoot

User-observed residual after f794832: creature stops to attack but
still runs slightly through the player before stopping.

Cause: at 4 m/s body velocity (RunAnimSpeed × ~1.0 speedMod) and a
60 fps tick (~16 ms), the body advances ~6.4 cm per tick. When dist
falls just below the 0.6 m DistanceToObject arrival threshold, the
arrival predicate fires and zeroes velocity — but the body has
already advanced one full tick INTO the threshold zone. That last
tick is the "running through" the user sees, especially when
combined with a player visual radius of ~0.5 m.

Fix: cap horizontal velocity in the steering branch so the body lands
EXACTLY at the arrival threshold instead of overshooting it. Pure
function in RemoteMoveToDriver (ClampApproachVelocity) so it's
testable; called from GameWindow.cs after apply_current_movement
sets RunForward velocity from the active cycle.

The clamp is a strict scale-down of the X/Y components; Z is left
to gravity / terrain handling. No-op for the flee branch — fleeing
has no overshoot risk by definition.

Tests: 1416 → 1420. Four new clamp scenarios: exact-landing (FP
tolerance), would-overshoot scale-down, already-at-threshold zeroing,
flee no-op.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -5226,6 +5226,23 @@ public sealed class GameWindow : IDisposable
                                 // updated orientation rotates that into the right
                                 // world direction toward the target.
                                 rm.Motion.apply_current_movement(cancelMoveTo: false, allowJump: false);
+
+                                // Clamp horizontal velocity so we don't overshoot
+                                // the arrival threshold during the final tick of
+                                // approach. Without this, a 4 m/s body advances
+                                // ~6 cm/tick and visibly runs slightly through
+                                // the target before the swing UM lands.
+                                float arrivalThreshold = rm.MoveToMoveTowards
+                                    ? rm.MoveToDistanceToObject
+                                    : rm.MoveToMinDistance;
+                                rm.Body.Velocity = AcDream.Core.Physics.RemoteMoveToDriver
+                                    .ClampApproachVelocity(
+                                        rm.Body.Position,
+                                        rm.Body.Velocity,
+                                        rm.MoveToDestinationWorld,
+                                        arrivalThreshold,
+                                        (float)dt,
+                                        rm.MoveToMoveTowards);
                             }
                         }
                     }