feat(physics): port retail complete object frame pipeline

Restore the named-retail object update order across local, remote, static, projectile, animation, shadow, teleport, and effect lifetimes. Separate authoritative root commits from spatial rebucketing, preserve per-owner hook/FIFO ordering, and remove update-path allocations with exact lifecycle and residency gates.

Add deterministic conformance, adversarial lifetime, GUID-reuse, pending-cell, quaternion, timestamp, and allocation coverage. Release build is warning-free and all 6,446 tests pass with five intentional skips; retail, architecture, and adversarial reviews are clean.

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

src/AcDream.Core/Physics/RetailObjectActivityGate.cs

@@ -0,0 +1,101 @@
+using System.Numerics;
+
+namespace AcDream.Core.Physics;
+
+/// <summary>
+/// Ports the lifecycle and 96-world-unit Active gate at the head of retail
+/// <c>CPhysicsObj::update_object</c> (0x00515D10) plus the inactive branch of
+/// <c>UpdateObjectInternal</c> (0x005156B0).
+/// </summary>
+public static class RetailObjectActivityGate
+{
+    public const float MaxPhysicsDistance = 96f;
+
+    public static RetailObjectActivityResult Evaluate(
+        RetailObjectQuantumClock clock,
+        PhysicsBody? body,
+        bool lifecycleEligible,
+        bool hasPartArray,
+        bool isStatic,
+        Vector3 objectPosition,
+        Vector3? playerPosition,
+        double elapsedSeconds)
+    {
+        ArgumentNullException.ThrowIfNull(clock);
+
+        if (!lifecycleEligible)
+        {
+            SetActive(clock, body, active: false);
+            return RetailObjectActivityResult.Suspended;
+        }
+
+        // Retail performs both the 96-unit decision and set_active(1) only
+        // while player_object exists. During login/session transitions a
+        // missing player preserves the prior Active state; it must not wake a
+        // previously distant object.
+        if (playerPosition is null)
+        {
+            if (clock.IsActive)
+                return RetailObjectActivityResult.Active;
+            clock.Advance(elapsedSeconds);
+            return RetailObjectActivityResult.Inactive;
+        }
+
+        bool withinActiveBubble = !hasPartArray
+            || Vector3.Distance(objectPosition, playerPosition.Value)
+                <= MaxPhysicsDistance;
+        if (!withinActiveBubble)
+        {
+            SetActive(clock, body, active: false);
+            // Inactive ordinary objects still consume update_time and run
+            // their particle/script tail. Those owners tick elsewhere in
+            // acdream; consuming the batch here prevents later catch-up.
+            clock.Advance(elapsedSeconds);
+            return RetailObjectActivityResult.Inactive;
+        }
+
+        // CPhysicsObj::set_active(1) (0x0050FC40) is a no-op for Static.
+        // Static objects that were initialized or removed from visibility
+        // inactive therefore stay on UpdateObjectInternal's particle/script
+        // tail instead of entering root physics.
+        bool reactivated = false;
+        if (!isStatic)
+        {
+            reactivated = clock.Activate();
+            if (body is not null)
+                body.TransientState |= TransientStateFlags.Active;
+        }
+
+        if (!clock.IsActive)
+        {
+            clock.Advance(elapsedSeconds);
+            return RetailObjectActivityResult.Inactive;
+        }
+
+        return reactivated
+            ? RetailObjectActivityResult.Reactivated
+            : RetailObjectActivityResult.Active;
+    }
+
+    private static void SetActive(
+        RetailObjectQuantumClock clock,
+        PhysicsBody? body,
+        bool active)
+    {
+        if (active)
+            clock.Activate();
+        else
+            clock.Deactivate();
+
+        if (body is not null && !active)
+            body.TransientState &= ~TransientStateFlags.Active;
+    }
+}
+
+public enum RetailObjectActivityResult
+{
+    Suspended,
+    Inactive,
+    Reactivated,
+    Active,
+}