fix(camera): complete retail in-head adjustment behavior

tests/AcDream.App.Tests/Rendering/RetailChaseCameraTests.cs

@@ -618,6 +618,60 @@ public class RetailChaseCameraTests
         Assert.Equal(MathF.Sqrt(0.6f * 0.6f + 0.5f * 0.5f), cam.Distance, 5);
     }
 
+    [Fact]
+    public void AdjustingCloserInRetailFirstPerson_RefusesNearWriteAndStaysInHead()
+    {
+        var cam = new RetailChaseCamera();
+        cam.SetRetailFirstPersonView();
+
+        cam.AdjustDistance(-1f);
+
+        Assert.True(cam.IsInHead);
+        Assert.Equal(0.18f, cam.Distance, 5);
+    }
+
+    [Fact]
+    public void AdjustPitchInRetailFirstPerson_ChangesDirectionWithoutMovingEye()
+    {
+        var cam = new RetailChaseCamera();
+        cam.SetRetailFirstPersonView();
+
+        cam.AdjustPitch(+1f);
+        cam.Update(
+            playerPosition: Vector3.Zero,
+            playerYaw: 0f,
+            playerVelocity: Vector3.Zero,
+            isOnGround: true,
+            contactPlaneNormal: Vector3.UnitZ,
+            dt: 1f / 60f);
+
+        Assert.True(cam.IsInHead);
+        Assert.Equal(new Vector3(0.18f, 0f, 1.5f), cam.Position);
+        Vector3 forward = Vector3.Normalize(new Vector3(
+            -cam.View.M13,
+            -cam.View.M23,
+            -cam.View.M33));
+        Assert.True(forward.Z > 0f);
+
+        for (int i = 0; i < 10; i++)
+            cam.AdjustPitch(+1f);
+        cam.Update(
+            playerPosition: Vector3.Zero,
+            playerYaw: 0f,
+            playerVelocity: Vector3.Zero,
+            isOnGround: true,
+            contactPlaneNormal: Vector3.UnitZ,
+            dt: 1f);
+        forward = Vector3.Normalize(new Vector3(
+            -cam.View.M13,
+            -cam.View.M23,
+            -cam.View.M33));
+        Assert.Equal(
+            0.8f / MathF.Sqrt(1f + 0.8f * 0.8f),
+            forward.Z,
+            5);
+    }
+
     [Fact]
     public void AdjustPitch_UsesRetailEightDegreeRotationAndPreservesLength()
     {