feat(item-acquire-history): controller + DTOs

Add ItemAcquireHistoryController (POST /item_acquire_history/info) with its
three DTOs and two integration tests (ordering + empty-viewer). The endpoint
reads ViewerAcquireHistory rows written by InventoryTransaction.CommitAsync,
ordered newest-first, capped at 300. Tests access doc.RootElement.histories
directly (no envelope wrapper in the test path — middleware skips non-UnityPlayer UA).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/ItemAcquireHistory/ItemAcquireHistoryInfoRequest.cs

@@ -0,0 +1,12 @@
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ItemAcquireHistory;
+
+/// <summary>
+/// Empty request body. The endpoint takes no parameters; this DTO exists so model binding
+/// resolves the envelope correctly.
+/// </summary>
+[MessagePackObject(true)]
+public sealed class ItemAcquireHistoryInfoRequest
+{
+}