refactor(world): extract live projection mechanics

Move appearance rebinding, collision construction, default-pose resolution, local shadow ownership, and exact leave-world presentation into focused owners. Preserve retail parent ordering with staged validation, committed recovery, recursive attached-subtree withdrawal, and retryable exact teardown across parent, pickup, position, unwield, and pose-loss edges.

Co-Authored-By: OpenAI Codex <codex@openai.com>

src/AcDream.App/Physics/LiveEntityDefaultPoseResolver.cs

@@ -0,0 +1,59 @@
+using AcDream.Core.Physics;
+using AcDream.Core.Physics.Motion;
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Types;
+
+namespace AcDream.App.Physics;
+
+/// <summary>
+/// Resolves the motion table's authored default-state part pose used by a
+/// live object's collision PartArray. Retail keeps the collision parts in the
+/// same current pose as the visual PartArray; an unresolved table falls back
+/// to Setup placement frames in <see cref="ShadowShapeBuilder"/>.
+/// The retained default-pose snapshot approximation is tracked as AP-84 in
+/// the retail divergence register until live per-frame collision poses land.
+/// </summary>
+internal sealed class LiveEntityDefaultPoseResolver
+{
+    private readonly Func<uint, MotionTable?> _loadMotionTable;
+    private readonly IAnimationLoader _animationLoader;
+    private readonly bool _dumpMotion;
+
+    public LiveEntityDefaultPoseResolver(
+        Func<uint, MotionTable?> loadMotionTable,
+        IAnimationLoader animationLoader,
+        bool dumpMotion)
+    {
+        _loadMotionTable = loadMotionTable
+            ?? throw new ArgumentNullException(nameof(loadMotionTable));
+        _animationLoader = animationLoader
+            ?? throw new ArgumentNullException(nameof(animationLoader));
+        _dumpMotion = dumpMotion;
+    }
+
+    public IReadOnlyList<Frame>? Resolve(uint motionTableId, int partCount)
+    {
+        if (motionTableId == 0u || partCount == 0)
+            return null;
+
+        MotionTable? motionTable = _loadMotionTable(motionTableId);
+        if (motionTable is null)
+            return null;
+
+        IReadOnlyList<Frame>? pose = MotionTablePose.DefaultStatePartFrames(
+            motionTable,
+            _animationLoader.LoadAnimation);
+
+        if (_dumpMotion)
+        {
+            string description = pose is null
+                ? "null->placement-fallback"
+                : FormattableString.Invariant(
+                    $"part0=({pose[0].Origin.X:F2},{pose[0].Origin.Y:F2},{pose[0].Origin.Z:F2})");
+            Console.WriteLine(FormattableString.Invariant(
+                $"[shape-pose] mt=0x{motionTableId:X8} parts={partCount} {description}"));
+        }
+
+        return pose;
+    }
+}