refactor(runtime): own per-session physics simulation

Move the sole PhysicsEngine, production cache, collision admissions, canonical bodies and hosts, remote components, ordinary/remote worksets, simulation, cell commits, and shadow synchronization under RuntimeEntityObjectLifetime. Keep App as the prepared-asset, animation-input, and render-projection adapter while preserving the named-retail update and collision order.

Add exact-incarnation, object-clock, callback-reentrancy, GUID-reuse, two-runtime isolation, source ownership, collision publication, and graphical projection coverage. Release build and the complete 8,588-test solution pass.

Co-authored-by: Codex <noreply@openai.com>

src/AcDream.Runtime/Physics/RuntimeRemoteMotionContracts.cs

@@ -0,0 +1,42 @@
+using System.Numerics;
+using AcDream.Core.Physics;
+using AcDream.Core.Physics.Motion;
+
+namespace AcDream.Runtime.Physics;
+
+public interface IRuntimeRemoteMotion
+{
+    PhysicsBody Body { get; }
+}
+
+public interface IRuntimePhysicsHostConsumer
+{
+    void BindPhysicsHost(Func<IPhysicsObjHost?> read);
+}
+
+public interface IRuntimeCanonicalPhysicsConsumer
+{
+    void BindCanonicalRuntime(
+        Func<IPhysicsObjHost?> readPhysicsHost,
+        Func<uint> readCell,
+        Action<uint> writeCell);
+}
+
+public interface IRuntimeCanonicalCellConsumer
+{
+    void BindCanonicalCell(Func<uint> read, Action<uint> write);
+}
+
+public interface IRuntimeRemotePlacement :
+    IRuntimeRemoteMotion,
+    IRuntimeCanonicalCellConsumer
+{
+    uint CellId { get; set; }
+    bool Airborne { get; set; }
+    Vector3 LastServerPosition { get; set; }
+    double LastServerPositionTime { get; set; }
+    Vector3 LastShadowSyncPosition { get; set; }
+    Quaternion LastShadowSyncOrientation { get; set; }
+    void HitGround();
+    void LeaveGround();
+}