fix(anim): clear dead-reckon state on entity respawn

When the server re-sends CreateObject for the same guid (visibility
refresh, appearance update, landblock crossing) we already drop the
old WorldEntity + animated entry + physics registration. Now also
clear the dead-reckon + last-move dicts keyed by the server guid so
the next UpdatePosition doesn't see leftover SnapResidual or
LastServerPos from the previous incarnation — which would make the
first position update look like a soft-snap transition.

Small fix, no new tests. 659 tests green.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -899,6 +899,12 @@ public sealed class GameWindow : IDisposable
             _animatedEntities.Remove(existingEntity.Id);
             // Physics collision registry entry is keyed by local id too.
             _physicsEngine.ShadowObjects.Deregister(existingEntity.Id);
+            // Dead-reckon state is keyed by SERVER guid (not local id) so we
+            // clear using the same guid the new spawn will use. Leaving old
+            // SnapResidual / DeadReckonedPos in would make the next first
+            // UpdatePosition look like a 2m-residual soft-snap.
+            _remoteDeadReckon.Remove(spawn.Guid);
+            _remoteLastMove.Remove(spawn.Guid);
         }
 
         // Log every spawn that arrives so we can inventory what the server