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>

tests/AcDream.App.Tests/Combat/CombatTargetControllerTests.cs

@@ -0,0 +1,82 @@
+using AcDream.App.Combat;
+using AcDream.Core.Combat;
+using AcDream.Core.Physics;
+using AcDream.Core.Selection;
+
+namespace AcDream.App.Tests.Combat;
+
+public sealed class CombatTargetControllerTests
+{
+    [Fact]
+    public void DeadSelectedTarget_AutoTargetEnabled_SelectsClosestReplacement()
+    {
+        var combat = new CombatState();
+        combat.SetCombatMode(CombatMode.Melee);
+        var selection = new SelectionState();
+        selection.Select(0x50000001u, SelectionChangeSource.World);
+        int calls = 0;
+        using var controller = new CombatTargetController(
+            combat,
+            selection,
+            autoTarget: () => true,
+            selectClosestTarget: () =>
+            {
+                calls++;
+                selection.Select(0x50000002u, SelectionChangeSource.System);
+                return 0x50000002u;
+            });
+
+        controller.OnMotionApplied(0x50000001u, MotionCommand.Dead);
+
+        Assert.Equal(1, calls);
+        Assert.Equal(0x50000002u, selection.SelectedObjectId);
+    }
+
+    [Fact]
+    public void DeadSelectedTarget_AutoTargetDisabled_LeavesSelectionClear()
+    {
+        var combat = new CombatState();
+        combat.SetCombatMode(CombatMode.Melee);
+        var selection = new SelectionState();
+        selection.Select(0x50000001u, SelectionChangeSource.World);
+        int calls = 0;
+        using var controller = new CombatTargetController(
+            combat, selection, () => false, () => { calls++; return null; });
+
+        controller.OnMotionApplied(0x50000001u, MotionCommand.Dead);
+
+        Assert.Equal(0, calls);
+        Assert.Null(selection.SelectedObjectId);
+    }
+
+    [Fact]
+    public void DeadSelectedTarget_NonCombatMode_DoesNotAutoTarget()
+    {
+        var combat = new CombatState();
+        var selection = new SelectionState();
+        selection.Select(0x50000001u, SelectionChangeSource.World);
+        int calls = 0;
+        using var controller = new CombatTargetController(
+            combat, selection, () => true, () => { calls++; return null; });
+
+        controller.OnMotionApplied(0x50000001u, MotionCommand.Dead);
+
+        Assert.Equal(0, calls);
+        Assert.Null(selection.SelectedObjectId);
+    }
+
+    [Fact]
+    public void DeadUnselectedObject_DoesNotDisturbCurrentTarget()
+    {
+        var combat = new CombatState();
+        combat.SetCombatMode(CombatMode.Missile);
+        var selection = new SelectionState();
+        selection.Select(0x50000002u, SelectionChangeSource.World);
+        using var controller = new CombatTargetController(
+            combat, selection, () => true, () => throw new InvalidOperationException());
+
+        controller.OnMotionApplied(0x50000001u, MotionCommand.Dead);
+
+        Assert.Equal(0x50000002u, selection.SelectedObjectId);
+    }
+}