feat(render): Phase A8.F — RetailChaseCamera consumes the camera-collision probe

Add ICameraCollisionProbe? CollisionProbe { get; init; } to RetailChaseCamera.
Extend Update() with optional cellId/selfEntityId params (default 0) so all
existing callers compile unchanged. After the exponential-damping block (step 5)
and before publishing Position/View (step 6), sweep _dampedEye through the
probe when CameraDiagnostics.CollideCamera is true and a probe is wired in
(step 5b). The fade computation in step 7 then naturally uses the collided eye.
Null probe and cellId=0 both short-circuit cleanly. Three new xUnit tests
cover: probe-wired+flag-on publishes collided eye, flag-off skips probe,
null probe doesn't throw. All 30 RetailChaseCameraTests pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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

@@ -445,4 +445,66 @@ public class RetailChaseCameraTests
         cam.AdjustPitch(+10f);
         Assert.Equal(RetailChaseCamera.PitchMax, cam.Pitch);
     }
+
+    // ── Camera collision (A8.F) ───────────────────────────────────────
+
+    private sealed class FakeProbe : ICameraCollisionProbe
+    {
+        public int Calls;
+        public Vector3 ReturnEye;
+        public Vector3 SweepEye(Vector3 pivot, Vector3 desiredEye, uint cellId, uint selfEntityId)
+        {
+            Calls++;
+            return ReturnEye;
+        }
+    }
+
+    [Fact]
+    public void Update_WithProbeAndFlagOn_PublishesCollidedEye()
+    {
+        CameraDiagnostics.CollideCamera = true;
+        var collided = new Vector3(1f, 2f, 3f);
+        var probe = new FakeProbe { ReturnEye = collided };
+        var cam = new RetailChaseCamera { CollisionProbe = probe };
+
+        cam.Update(
+            playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+            isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+            cellId: 0x100, selfEntityId: 0x5);
+
+        Assert.True(probe.Calls >= 1);
+        Assert.Equal(collided, cam.Position);
+    }
+
+    [Fact]
+    public void Update_FlagOff_DoesNotConsultProbe()
+    {
+        CameraDiagnostics.CollideCamera = false;
+        var probe = new FakeProbe { ReturnEye = new Vector3(99f, 99f, 99f) };
+        var cam = new RetailChaseCamera { CollisionProbe = probe };
+
+        cam.Update(
+            playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+            isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+            cellId: 0x100, selfEntityId: 0x5);
+
+        Assert.Equal(0, probe.Calls);
+        Assert.NotEqual(new Vector3(99f, 99f, 99f), cam.Position);
+
+        CameraDiagnostics.CollideCamera = true; // reset
+    }
+
+    [Fact]
+    public void Update_NullProbe_DoesNotThrow()
+    {
+        CameraDiagnostics.CollideCamera = true;
+        var cam = new RetailChaseCamera { CollisionProbe = null };
+
+        cam.Update(
+            playerPosition: Vector3.Zero, playerYaw: 0f, playerVelocity: Vector3.Zero,
+            isOnGround: true, contactPlaneNormal: Vector3.UnitZ, dt: 1f / 60f,
+            cellId: 0x100, selfEntityId: 0x5);
+
+        Assert.NotEqual(default, cam.View);
+    }
 }