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.

src/AcDream.App/Rendering/GameWindow.cs

@@ -2273,16 +2273,30 @@ public sealed class GameWindow : IDisposable
             //   command == null      → retail stop signal → Ready
             //   command.Value == 0   → explicit 0 (rare)   → Ready
             //   otherwise            → resolve class byte and use full cmd
+            float speedMod = update.MotionState.ForwardSpeed ?? 1f;
             uint fullMotion;
             if ((!command.HasValue || command.Value == 0)
                 && update.MotionState.IsServerControlledMoveTo)
             {
-                // MoveTo packets preserve the current cycle until velocity
-                // chooses the visible walk/run/ready state.
                 uint current = ae.Sequencer.CurrentMotion;
-                fullMotion = (current & 0xFF000000u) != 0
-                    ? current
-                    : AcDream.Core.Physics.MotionCommand.Ready;
+                if (IsRemoteLocomotion(current))
+                {
+                    // MoveTo packets preserve an active locomotion cycle;
+                    // position velocity will refine the speed.
+                    fullMotion = current;
+                }
+                else
+                {
+                    // Retail MoveToManager::BeginMoveForward calls
+                    // MovementParameters::get_command (0x0052AA00), then
+                    // _DoMotion -> adjust_motion. With default CanRun and
+                    // enough distance, WalkForward + HoldKey_Run becomes
+                    // RunForward immediately, before the next position echo.
+                    var seed = AcDream.Core.Physics.ServerControlledLocomotion
+                        .PlanMoveToStart();
+                    fullMotion = seed.Motion;
+                    speedMod = seed.SpeedMod;
+                }
             }
             else if (!command.HasValue || command.Value == 0)
             {
@@ -2313,8 +2327,6 @@ public sealed class GameWindow : IDisposable
             // apply_run_to_command). Treating zero as "unspecified / 1.0"
             // produces "slow walk that never stops" — exactly what the
             // stop bug looked like.
-            float speedMod = update.MotionState.ForwardSpeed ?? 1f;
-
             if (Environment.GetEnvironmentVariable("ACDREAM_DUMP_MOTION") == "1"
                 && update.Guid != _playerServerGuid)
                 Console.WriteLine(

src/AcDream.Core/Physics/ServerControlledLocomotion.cs

@@ -32,6 +32,13 @@ public static class ServerControlledLocomotion
     public const float MinSpeedMod = 0.25f;
     public const float MaxSpeedMod = 3.00f;
 
+    // Retail MoveToManager::BeginMoveForward -> MovementParameters::get_command
+    // (0x0052AA00) seeds forward motion before the next position update.
+    public static LocomotionCycle PlanMoveToStart()
+    {
+        return new LocomotionCycle(MotionCommand.RunForward, 1f, true);
+    }
+
     public static LocomotionCycle PlanFromVelocity(Vector3 worldVelocity)
     {
         float horizontalSpeed = MathF.Sqrt(

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()
     {