fix(anim): Phase L.1c seed move-to locomotion

Retail MoveToManager::BeginMoveForward calls MovementParameters::get_command (0x0052AA00) and then _DoMotion/adjust_motion, so a server-controlled MoveTo begins visible forward locomotion before the next UpdatePosition echo. Seed RunForward for MoveTo packets that omit ForwardCommand, while preserving active locomotion and letting position velocity refine walk/run/stop.

tests/AcDream.Core.Tests/Physics/ServerControlledLocomotionTests.cs

@@ -6,6 +6,16 @@ namespace AcDream.Core.Tests.Physics;
 
 public sealed class ServerControlledLocomotionTests
 {
+    [Fact]
+    public void PlanMoveToStart_SeedsImmediateRunCycle()
+    {
+        var plan = ServerControlledLocomotion.PlanMoveToStart();
+
+        Assert.True(plan.IsMoving);
+        Assert.Equal(MotionCommand.RunForward, plan.Motion);
+        Assert.Equal(1.0f, plan.SpeedMod);
+    }
+
     [Fact]
     public void PlanFromVelocity_StopsBelowRetailNoiseThreshold()
     {