feat(chat): Campaign CH slice CH3 — side-channel membership, wire, and echo parity

Ports retail's SendTurbineChat (@0x0057db10) local pre-send membership gate
so Roleplay/Society/Olthoi stop silently swallowing outbound chat: a new
TurbineChatMembershipGate checks Turbine availability and the player's own
Hear*Chat option before sending, raising "Turbine chat is not available."
or the 0x0551 YouAreNotListeningTo_Channel refusal through the CH2 AddText
chokepoint instead. Wired into both the graphical (LiveSessionCommandRouter)
and headless (DirectGameRuntimeCommandAdapter) send paths so they can't
diverge. Retracts the 26-day-old false "ACE doesn't run a TurbineChat
server" claim from ISSUES.md, the roadmap, and project_chat_pipeline.md —
ACE's TurbineChat implementation is complete and on by default; the real
bug was treating Hear*Chat as a display filter instead of room membership.

Also: implements SetSingleCharacterOption (0x0005), the only wire message
that actually joins/leaves a Turbine room, and wires the five Settings Chat
toggles to it (publish on Save, changed bits only) plus seeds ChatSettings
from the server's own CharacterOptions2 on every PlayerDescription. Fixes
the legacy-channel double-print (Fellow/Vassals/Patron/Monarch/CoVassals
skip the local echo now that ChatChannelInfo.IsSelfEchoChannel is finally
consulted). Routes /a to Turbine unconditionally (retail's @a never falls
back to the legacy bitflag) and adds /ab for the legacy AllegianceBroadcast
verb retail actually has. Surfaces a nonzero TurbineChat ack HResult instead
of discarding it silently. Deletes the malformed, callerless SetCharacterOptions
(0x01A1) and AddChannel/RemoveChannel (0x0145/0x0146) builders.

Files every AC-specific algorithm change cites the named retail decomp
(SendTurbineChat 0x0057db10, StartupTurbineChatSystem 0x0057EFB0,
GameActionSetSingleCharacterOption) plus ACE/holtburger cross-checks.
Register rows AP-181 (no client-side spam throttle) and UN-9 (an
incidentally-discovered CharacterOptions1.Default literal mismatch, not
investigated further) filed per the divergence-register rule.

11,957 passed / 4 skipped / 0 failed (full Release suite, up from the
11,916/4/0 baseline).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.Core/Chat/ChatChannelInfo.cs

@@ -50,6 +50,14 @@ public abstract record ChatChannelInfo(string DisplayName, ChatChannelSource Sou
             // channels are the ones the server echoes back to the sender
             // with an empty sender field. Bitflag values from
             // references/holtburger/.../messages/chat/types.rs::ChatChannel.
+            //
+            // CH3 (2026-08-09, research doc §3.7/§5.4): AllegianceBroadcast
+            // (0x02000000) deliberately falls to the `false` default below —
+            // ACE's GameActionChatChannel handler includes the sender in the
+            // normal real-name member broadcast for that channel (no
+            // separate "" -sender echo the way Fellow/Vassals/Patron/
+            // Monarch/CoVassals get), so the client must keep its own local
+            // optimistic echo or the sender never sees their own line.
             return ChannelId switch
             {
                 0x00000800u => true,  // Fellow

src/AcDream.Core/Chat/ClientTextRefusals.cs

@@ -106,4 +106,21 @@ public static class ClientTextRefusals
     /// "You can't use chat emotes from t…".
     /// </summary>
     public const string CantEmotePosition = "You can't use chat emotes from this position";
+
+    /// <summary>
+    /// Campaign CH slice CH3 (2026-08-09): retail
+    /// <c>ClientCommunicationSystem::SendTurbineChat @0x0057db10</c>'s local
+    /// refusal when Turbine chat is disabled or the target room id is 0 (no
+    /// allegiance, no society, etc.) — raised BEFORE any wire send, exactly
+    /// like the jump refusals above. Byte-read off the PDB-paired binary at
+    /// <c>0x007e0d1c</c>: <c>"Turbine chat is not available.\n"</c>. The call
+    /// site (<c>0057dd64</c>) passes type <c>0</c> (Default), not <c>0x1A</c>
+    /// (ClientLocal) — confirmed by direct comparison against the
+    /// unambiguous <c>cant_jump_in_air</c> call sites, which use the same
+    /// <c>AddTextToScroll(this, &amp;text, type, allowPluginFilter,
+    /// windowId)</c> argument order with a literal <c>0x1a</c> in the type
+    /// slot; this call has a literal <c>0</c> there instead. So this
+    /// refusal lands in the chat transcript, not the SpewBox.
+    /// </summary>
+    public const string TurbineChatUnavailable = "Turbine chat is not available.";
 }