feat(net+chat): #19 TurbineChat (0xF7DE) codec + ChatChannelInfo + SetTurbineChatChannels parser

Full port of holtburger's TurbineChat sidecar wire path:

- TurbineChat.cs: 0xF7DE codec with three payload variants
  (EventSendToRoom S->C, RequestSendToRoomById C->S, Response).
  10-field outer header (size_first/blob_type/dispatch_type/
  target_type/target_id/transport_type/transport_id/cookie/
  size_second + payload).
- UTF-16LE turbine string codec with 1-or-2 byte variable-length
  prefix (high bit on first byte signals 2-byte form). Mirrors
  holtburger's read_turbine_string / write_turbine_string at
  references/holtburger/.../messages/chat/turbine.rs:502-544.
- SetTurbineChatChannels.cs: 0x0295 GameEvent sub-opcode parser
  (10 x u32 channel ids). Wired through GameEventDispatcher in
  WorldSession ctor; routes to GameEventWiring + TurbineChatState.
- ChatChannelInfo.cs (Core): unified record union with Legacy
  (channel id + name) and Turbine (room id + chat type +
  dispatch type + name) variants, plus IsSelfEchoChannel
  predicate (Tells = false, channels = true so optimistic echo
  is suppressed where the server will echo).
- TurbineChatState.cs (Core): Enabled flag + 10 cached room ids
  + NextContextId() cookie counter starting at 1.
- WorldSession adds TurbineChatReceived + TurbineChannelsReceived
  events; SendTurbineChatTo outbound builds RequestSendToRoomById
  + sends through SendGameAction. ProcessDatagram dispatches
  0xF7DE at the top level.
- GameWindow constructs TurbineChatState, subscribes inbound
  EventSendToRoom -> ChatLog.OnChannelBroadcast; extends I.3's
  SendChatCmd handler to route Turbine kinds (General/Trade/Lfg/
  Roleplay/Society/Olthoi) through TurbineChat first, fall back
  to legacy ChatChannel send when state.Enabled == false.

Round-trip golden fixtures from holtburger source verified for
all three payload variants + UTF-16LE strings (short + long
prefix + non-ASCII Cafe + empty) + SetTurbineChatChannels.

26 new tests:
- TurbineChatTests, SetTurbineChatChannelsTests in Core.Net.Tests
- ChatChannelInfoTests, TurbineChatStateTests in Core.Tests

Solution total: 960 green (243 Core.Net + 625 Core + 92 UI).

ACE doesn't run a TurbineChat server, so codec is "ready when
needed" for retail-server-emulating setups. Legacy ChatChannel
fallback continues to work for current ACE-against-acdream play.

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

tests/AcDream.Core.Tests/Chat/ChatChannelInfoTests.cs

@@ -0,0 +1,61 @@
+using AcDream.Core.Chat;
+using Xunit;
+
+namespace AcDream.Core.Tests.Chat;
+
+/// <summary>
+/// Phase I.6: <see cref="ChatChannelInfo"/> + <see cref="ChatChannelSource"/>
+/// behaviour. Mirrors holtburger's <c>is_self_echo_channel</c> predicate
+/// (chat.rs:492-507) — only the legacy fellowship + allegiance-tree
+/// channels echo the sender's own messages back with empty sender.
+/// </summary>
+public sealed class ChatChannelInfoTests
+{
+    [Fact]
+    public void Legacy_FellowshipBitflag_IsSelfEcho()
+    {
+        var c = new ChatChannelInfo.Legacy(0x00000800u, "Fellowship");
+        Assert.Equal(ChatChannelSource.Legacy, c.Source);
+        Assert.Equal("Fellowship", c.DisplayName);
+        Assert.True(c.IsSelfEchoChannel());
+    }
+
+    [Theory]
+    [InlineData(0x00001000u)]  // Vassals
+    [InlineData(0x00002000u)]  // Patron
+    [InlineData(0x00004000u)]  // Monarch
+    [InlineData(0x01000000u)]  // CoVassals
+    public void Legacy_AllegianceTreeBitflags_AreSelfEcho(uint id)
+    {
+        var c = new ChatChannelInfo.Legacy(id, "Allegiance");
+        Assert.True(c.IsSelfEchoChannel(), $"channel 0x{id:X8} should self-echo");
+    }
+
+    [Fact]
+    public void Legacy_AllegianceBroadcastBitflag_IsNOTSelfEcho()
+    {
+        // 0x02000000 AllegianceBroadcast is the read-only motd channel —
+        // server does not echo client messages back on it (per holtburger
+        // chat.rs:492-507 predicate, only Fellow+Vassals+Patron+Monarch+CoVassals).
+        var c = new ChatChannelInfo.Legacy(0x02000000u, "AllegianceBroadcast");
+        Assert.False(c.IsSelfEchoChannel());
+    }
+
+    [Fact]
+    public void Turbine_IsNeverSelfEcho()
+    {
+        // Turbine rooms don't echo — caller must emit local optimistic echo.
+        var t = new ChatChannelInfo.Turbine(
+            RoomId: 0x12345678u, ChatType: 2u, DispatchType: 2u, DisplayName: "General");
+        Assert.Equal(ChatChannelSource.Turbine, t.Source);
+        Assert.Equal("General", t.DisplayName);
+        Assert.False(t.IsSelfEchoChannel());
+    }
+
+    [Fact]
+    public void Legacy_UnknownBitflag_IsNotSelfEcho()
+    {
+        var c = new ChatChannelInfo.Legacy(0xCAFEF00Du, "WatCha");
+        Assert.False(c.IsSelfEchoChannel());
+    }
+}

tests/AcDream.Core.Tests/Chat/TurbineChatStateTests.cs

@@ -0,0 +1,84 @@
+using AcDream.Core.Chat;
+using Xunit;
+
+namespace AcDream.Core.Tests.Chat;
+
+/// <summary>
+/// Phase I.6: <see cref="TurbineChatState"/> behaviour.
+/// </summary>
+public sealed class TurbineChatStateTests
+{
+    [Fact]
+    public void InitialState_DisabledAndZeroRooms_NextContextIdStartsAt1()
+    {
+        var s = new TurbineChatState();
+        Assert.False(s.Enabled);
+        Assert.Equal(0u, s.GeneralRoom);
+        Assert.Equal(0u, s.TradeRoom);
+        Assert.Equal(0u, s.AllegianceRoom);
+        Assert.Equal(1u, s.NextContextId());
+        // After consuming one cookie, the next is 2
+        Assert.Equal(2u, s.NextContextId());
+    }
+
+    [Fact]
+    public void OnChannelsReceived_PopulatesAllFieldsAndEnables()
+    {
+        var s = new TurbineChatState();
+        s.OnChannelsReceived(
+            allegianceRoom: 0xA0,
+            generalRoom: 0xA1,
+            tradeRoom: 0xA2,
+            lfgRoom: 0xA3,
+            roleplayRoom: 0xA4,
+            olthoiRoom: 0xA5,
+            societyRoom: 0xA6,
+            societyCelestialHandRoom: 0xA7,
+            societyEldrytchWebRoom: 0xA8,
+            societyRadiantBloodRoom: 0xA9);
+
+        Assert.True(s.Enabled);
+        Assert.Equal(0xA0u, s.AllegianceRoom);
+        Assert.Equal(0xA1u, s.GeneralRoom);
+        Assert.Equal(0xA2u, s.TradeRoom);
+        Assert.Equal(0xA3u, s.LfgRoom);
+        Assert.Equal(0xA4u, s.RoleplayRoom);
+        Assert.Equal(0xA5u, s.OlthoiRoom);
+        Assert.Equal(0xA6u, s.SocietyRoom);
+        Assert.Equal(0xA7u, s.SocietyCelestialHandRoom);
+        Assert.Equal(0xA8u, s.SocietyEldrytchWebRoom);
+        Assert.Equal(0xA9u, s.SocietyRadiantBloodRoom);
+    }
+
+    [Fact]
+    public void NextContextId_IsMonotonicAndStartsAt1()
+    {
+        var s = new TurbineChatState();
+        Assert.Equal(1u, s.NextContextId());
+        Assert.Equal(2u, s.NextContextId());
+        Assert.Equal(3u, s.NextContextId());
+        Assert.Equal(4u, s.NextContextId());
+    }
+
+    [Fact]
+    public void RoomFor_ReturnsConfiguredRoom()
+    {
+        var s = new TurbineChatState();
+        s.OnChannelsReceived(
+            allegianceRoom: 1, generalRoom: 2, tradeRoom: 3,
+            lfgRoom: 4, roleplayRoom: 5, olthoiRoom: 6,
+            societyRoom: 7, societyCelestialHandRoom: 8,
+            societyEldrytchWebRoom: 9, societyRadiantBloodRoom: 10);
+
+        Assert.Equal(1u,  s.RoomFor(ChatChannelKindLite.Allegiance));
+        Assert.Equal(2u,  s.RoomFor(ChatChannelKindLite.General));
+        Assert.Equal(3u,  s.RoomFor(ChatChannelKindLite.Trade));
+        Assert.Equal(4u,  s.RoomFor(ChatChannelKindLite.Lfg));
+        Assert.Equal(5u,  s.RoomFor(ChatChannelKindLite.Roleplay));
+        Assert.Equal(6u,  s.RoomFor(ChatChannelKindLite.Olthoi));
+        Assert.Equal(7u,  s.RoomFor(ChatChannelKindLite.Society));
+        Assert.Equal(8u,  s.RoomFor(ChatChannelKindLite.SocietyCelestialHand));
+        Assert.Equal(9u,  s.RoomFor(ChatChannelKindLite.SocietyEldrytchWeb));
+        Assert.Equal(10u, s.RoomFor(ChatChannelKindLite.SocietyRadiantBlood));
+    }
+}