feat(items): Phase F.2 ItemRepository + AppraiseRequest round-trip

Implements the item-state mirror + appraise round-trip infrastructure
on top of Phase F.1's GameEvent dispatcher.

Core layer (AcDream.Core/Items):
- ItemRepository: ConcurrentDictionary-backed live item state keyed by
  server ObjectId. Events: ItemAdded, ItemMoved, ItemRemoved,
  ItemPropertiesUpdated. MoveItem handles container / slot / equip
  location updates atomically and fires ItemMoved with old+new container
  ids. UpdateProperties merges a PropertyBundle patch (for appraise
  results) without clobbering existing untouched keys.

Wire layer (AcDream.Core.Net/Messages):
- AppraiseRequest (0x00C8 C→S, inside 0xF7B1 GameAction envelope):
  Build(sequence, targetGuid) → 16-byte body ready for SendGameAction.
- GameEvents.ParseIdentifyResponseHeader for 0x00C9 S→C — extracts
  (guid, appraiseFlags, success). Full PropertyBundle deserialization
  (the 10-flag bitfield-indexed tables) is a future pass; header alone
  is enough to route into the repository + surface "appraise complete"
  to UI.
- GameEvents.ParseWieldObject (0x0023) — server-driven equip.
- GameEvents.ParsePutObjInContainer (0x0022) — server-driven inventory
  move (item, container, placement).

Tests (11 new):
- ItemRepository: add/update fires correct event, move updates fields,
  missing-id returns false, remove, properties merge, clear.
- Wire: AppraiseRequest byte-exact encoding, IdentifyResponse header
  round-trip, WieldObject round-trip, PutObjInContainer round-trip.

Build green, 532 tests pass (up from 521).

Phase F.2 unblocks the Paperdoll + Inventory UI panels and the
"appraise on right-click" UX. Next pieces: PropertyBundle full
deserializer (AppraiseInfo 10-flag bitfield), outbound move/drop/
pickup actions.

Ref: r06 §1 (ItemType), §2 (EquipMask), §5 (appraise wire), §7 (pack
depth rules).
Ref: ACE GameEventIdentifyObjectResponse.cs for AppraiseInfo format.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/AcDream.Core.Net.Tests/Messages/AppraiseTests.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Buffers.Binary;
+using AcDream.Core.Net.Messages;
+using Xunit;
+
+namespace AcDream.Core.Net.Tests.Messages;
+
+public sealed class AppraiseTests
+{
+    [Fact]
+    public void AppraiseRequest_Build_EmitsCorrectWireBytes()
+    {
+        byte[] body = AppraiseRequest.Build(gameActionSequence: 7, targetGuid: 0x12345678u);
+
+        Assert.Equal(16, body.Length);
+        Assert.Equal(AppraiseRequest.GameActionEnvelope,
+            BinaryPrimitives.ReadUInt32LittleEndian(body));
+        Assert.Equal(7u,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(4)));
+        Assert.Equal(AppraiseRequest.SubOpcode,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(8)));
+        Assert.Equal(0x12345678u,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(12)));
+    }
+
+    [Fact]
+    public void ParseIdentifyResponseHeader_RoundTrip()
+    {
+        byte[] payload = new byte[12];
+        BinaryPrimitives.WriteUInt32LittleEndian(payload,            0xDEADBEEFu);   // guid
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(4),  0x000F);          // flags
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(8),  1u);              // success
+
+        var parsed = GameEvents.ParseIdentifyResponseHeader(payload);
+        Assert.NotNull(parsed);
+        Assert.Equal(0xDEADBEEFu, parsed!.Value.Guid);
+        Assert.Equal(0x000Fu, parsed.Value.AppraiseFlags);
+        Assert.True(parsed.Value.Success);
+    }
+
+    [Fact]
+    public void ParseWieldObject_RoundTrip()
+    {
+        byte[] payload = new byte[12];
+        BinaryPrimitives.WriteUInt32LittleEndian(payload,            0x1000u);
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(4),  0x00400000u);  // MeleeWeapon slot
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(8),  0x2000u);      // wielder
+
+        var parsed = GameEvents.ParseWieldObject(payload);
+        Assert.NotNull(parsed);
+        Assert.Equal(0x1000u, parsed!.Value.ItemGuid);
+        Assert.Equal(0x00400000u, parsed.Value.EquipLoc);
+        Assert.Equal(0x2000u, parsed.Value.WielderGuid);
+    }
+
+    [Fact]
+    public void ParsePutObjInContainer_RoundTrip()
+    {
+        byte[] payload = new byte[12];
+        BinaryPrimitives.WriteUInt32LittleEndian(payload,            0x1001u);
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(4),  0x2001u);
+        BinaryPrimitives.WriteUInt32LittleEndian(payload.AsSpan(8),  3u);
+
+        var parsed = GameEvents.ParsePutObjInContainer(payload);
+        Assert.NotNull(parsed);
+        Assert.Equal(0x1001u, parsed!.Value.ItemGuid);
+        Assert.Equal(0x2001u, parsed.Value.ContainerGuid);
+        Assert.Equal(3u,      parsed.Value.Placement);
+    }
+}

tests/AcDream.Core.Tests/Items/ItemRepositoryTests.cs

@@ -0,0 +1,119 @@
+using AcDream.Core.Items;
+using Xunit;
+
+namespace AcDream.Core.Tests.Items;
+
+public sealed class ItemRepositoryTests
+{
+    private static ItemInstance MakeItem(uint id, string name = "Widget") =>
+        new ItemInstance
+        {
+            ObjectId = id,
+            WeenieClassId = 1,
+            Name = name,
+            Type = ItemType.Misc,
+            StackSize = 1,
+            Burden = 10,
+            Value = 5,
+        };
+
+    [Fact]
+    public void AddOrUpdate_FiresAddedEvent()
+    {
+        var repo = new ItemRepository();
+        ItemInstance? added = null;
+        repo.ItemAdded += i => added = i;
+
+        var item = MakeItem(100);
+        repo.AddOrUpdate(item);
+
+        Assert.Same(item, added);
+        Assert.Equal(1, repo.ItemCount);
+        Assert.Same(item, repo.GetItem(100));
+    }
+
+    [Fact]
+    public void AddOrUpdate_ExistingItem_FiresPropertiesUpdated()
+    {
+        var repo = new ItemRepository();
+        var item = MakeItem(100);
+        repo.AddOrUpdate(item);
+
+        int propUpdateCount = 0;
+        repo.ItemPropertiesUpdated += _ => propUpdateCount++;
+
+        repo.AddOrUpdate(item);    // second call is an update
+        Assert.Equal(1, propUpdateCount);
+    }
+
+    [Fact]
+    public void MoveItem_UpdatesContainerAndFiresEvent()
+    {
+        var repo = new ItemRepository();
+        var item = MakeItem(100);
+        repo.AddOrUpdate(item);
+
+        uint seenOld = 999, seenNew = 999;
+        repo.ItemMoved += (it, oldC, newC) => { seenOld = oldC; seenNew = newC; };
+
+        repo.MoveItem(100, 42, newSlot: 3);
+
+        Assert.Equal(0u, seenOld);   // was not in any container initially
+        Assert.Equal(42u, seenNew);
+        Assert.Equal(42u, item.ContainerId);
+        Assert.Equal(3,   item.ContainerSlot);
+    }
+
+    [Fact]
+    public void MoveItem_Nonexistent_ReturnsFalse()
+    {
+        var repo = new ItemRepository();
+        Assert.False(repo.MoveItem(999, 42));
+    }
+
+    [Fact]
+    public void Remove_FiresEventAndRemoves()
+    {
+        var repo = new ItemRepository();
+        var item = MakeItem(100);
+        repo.AddOrUpdate(item);
+
+        ItemInstance? removed = null;
+        repo.ItemRemoved += i => removed = i;
+
+        Assert.True(repo.Remove(100));
+        Assert.Same(item, removed);
+        Assert.Null(repo.GetItem(100));
+    }
+
+    [Fact]
+    public void UpdateProperties_MergesIncomingBundle()
+    {
+        var repo = new ItemRepository();
+        var item = MakeItem(100);
+        item.Properties.Ints[1] = 10;
+        repo.AddOrUpdate(item);
+
+        var patch = new PropertyBundle();
+        patch.Ints[2] = 20;          // new
+        patch.Ints[1] = 15;          // overrides
+        patch.Strings[100] = "desc";
+        repo.UpdateProperties(100, patch);
+
+        Assert.Equal(15, item.Properties.Ints[1]);
+        Assert.Equal(20, item.Properties.Ints[2]);
+        Assert.Equal("desc", item.Properties.Strings[100]);
+    }
+
+    [Fact]
+    public void Clear_RemovesAllItems()
+    {
+        var repo = new ItemRepository();
+        repo.AddOrUpdate(MakeItem(1));
+        repo.AddOrUpdate(MakeItem(2));
+        repo.AddOrUpdate(MakeItem(3));
+
+        repo.Clear();
+        Assert.Equal(0, repo.ItemCount);
+    }
+}