feat(inventory): port retail item giving (#216)

Preserve SmartBox drag-release coordinates, route the picked 3-D target through the retail AttemptPlaceIn3D policy, and send authoritative GiveObject requests with the selected stack quantity. Honor PlayerDescription's player secure-trade option and document the remaining trade-system boundary.

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

tests/AcDream.Core.Net.Tests/WorldSessionInventoryActionTests.cs

@@ -45,4 +45,19 @@ public sealed class WorldSessionInventoryActionTests
 
         Assert.Equal(InventoryActions.BuildStackableSplitTo3D(1, 0xAAu, 2u), captured);
     }
+
+    [Fact]
+    public void SendGiveObject_UsesNextSequenceAndExactBuilderBytes()
+    {
+        using var session = new WorldSession(
+            new IPEndPoint(IPAddress.Loopback, 65000));
+        byte[]? captured = null;
+        session.GameActionCapture = body => captured = body;
+
+        session.SendGiveObject(targetGuid: 0xAAu, itemGuid: 0xBBu, amount: 3u);
+
+        Assert.Equal(
+            InventoryActions.BuildGiveObjectRequest(1, 0xAAu, 0xBBu, 3u),
+            captured);
+    }
 }