fix(combat): persist death and retarget on kill

Keep the velocity-only NPC adaptation inside the locomotion family so authoritative Dead motion remains persistent. Route selection clears through a dedicated combat target controller that reacquires the closest eligible creature when retail Auto Target conditions apply.

Co-Authored-By: Codex <codex@openai.com>

src/AcDream.Core/Physics/ServerControlledLocomotion.cs

@@ -61,6 +61,21 @@ public static class ServerControlledLocomotion
             true);
     }
 
+    /// <summary>
+    /// Limits the AP-80 position-velocity adaptation to the locomotion state
+    /// family it exists to supply. Retail UpdatePosition never selects a
+    /// motion at all; therefore an authoritative action/substate such as Dead
+    /// must never be replaced by this adaptation.
+    /// </summary>
+    public static bool CanApplyVelocityCycle(uint currentMotion)
+        => currentMotion == MotionCommand.Ready || IsLocomotion(currentMotion);
+
+    public static bool IsLocomotion(uint motion)
+    {
+        uint low = motion & 0xFFu;
+        return low is 0x05 or 0x06 or 0x07 or 0x0F or 0x10;
+    }
+
     public readonly record struct LocomotionCycle(
         uint Motion,
         float SpeedMod,

src/AcDream.Core/Selection/SelectionState.cs

@@ -19,6 +19,7 @@ public enum SelectionChangeReason
     Selected,
     Cleared,
     SelectedObjectRemoved,
+    CombatTargetDied,
     PreviousSelection,
 }