fix(combat): escape occupied login positions

Port retail's radius-aware placement ring so a relogging player is seated beside creatures occupying the saved location, and register the local body in the shared resolved-shadow pipeline. Route new forward movement and jump through AbortAutomaticAttack so repeat combat cancels immediately on movement.

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

src/AcDream.App/Physics/ShadowPositionSynchronizer.cs

@@ -0,0 +1,39 @@
+using System.Numerics;
+using AcDream.Core.Physics;
+
+namespace AcDream.App.Physics;
+
+/// <summary>
+/// Shared host adapter for retail's moved-object shadow re-registration
+/// (<c>CPhysicsObj::SetPositionInternal</c> 0x00515330). Both the local body
+/// and remote dead-reckoning bodies publish their resolved position through
+/// this one cell-offset calculation.
+/// </summary>
+internal static class ShadowPositionSynchronizer
+{
+    public static void Sync(
+        ShadowObjectRegistry registry,
+        uint entityId,
+        Vector3 position,
+        Quaternion orientation,
+        uint cellId,
+        int liveCenterX,
+        int liveCenterY)
+    {
+        if (cellId == 0)
+            return;
+
+        int landblockX = (int)((cellId >> 24) & 0xFFu);
+        int landblockY = (int)((cellId >> 16) & 0xFFu);
+        float worldOffsetX = (landblockX - liveCenterX) * 192f;
+        float worldOffsetY = (landblockY - liveCenterY) * 192f;
+        registry.UpdatePosition(
+            entityId,
+            position,
+            orientation,
+            worldOffsetX,
+            worldOffsetY,
+            cellId,
+            seedCellId: cellId);
+    }
+}