feat(chat): Phase J - welcome message + own-echo dedup + long-form slash aliases + WeenieError templates

Six fixes from the 2026-04-25 live verify session.

1. ServerMessage (0xF7E0) wired to ChatLog. ACE's
   GameMessageSystemChat - used for the login banner "Welcome to
   Asheron's Call ... powered by ACEmulator ... type @acehelp" plus
   any future server broadcast - rides opcode 0xF7E0. The parser
   shipped in I.5 but the WorldSession.ServerMessageReceived event
   was never subscribed by GameWindow, so the welcome line was
   silently dropped. Subscribed now; same wave wires the missing
   EmoteHeard / SoulEmoteHeard / PlayerKilledReceived events that
   I.5 also left orphan.

2. Drop optimistic /say echo + plumb local-player-guid into ChatLog.
   ACE's HandleActionTalk broadcasts a HearSpeech back to the sender
   too, so we were double-printing every /say (own optimistic +
   server echo). New ChatLog.SetLocalPlayerGuid() pushes the chosen
   character guid in (mirrors VitalsVM pattern); OnLocalSpeech
   detects own-guid match and substitutes Sender="" so the formatter
   's IsOwnSpeaker path renders "You say, ..." instead of
   "+Acdream says, ...". Single line per /say.

3. IsOwnSpeaker check now applies to ChatKind.Channel too. Empty/
   "You" sender -> "[Allegiance] You say, \"text\"" instead of the
   "[Allegiance]  says, \"text\"" double-space hole that Phase I.6's
   OnSelfSent left when echoing legacy ChatChannel sends.

4. Long-form slash aliases: /general /allegiance /patron /vassals
   /monarch /covassals /fellowship /fellow /lookingforgroup
   /roleplay /rp /tr /gen, plus /s as alias for /say. Retail muscle
   memory expected these; the prior parser only recognized /g /a /p
   /v /m /cv /lfg /role and friends, so "/patron hello" fell
   through as /say with the literal "/patron" prefix.

5. WeenieError templates filled in for the codes the user hit:
   - 0x0414 YouAreNotInAllegiance  -> "You are not in an allegiance!"
   - 0x050F YouDoNotBelongToAFellowship -> "You do not belong to a Fellowship."
   Replaces the cryptic "WeenieError 0x0414" / "0x050F" lines.

6. @ command pass-through: ACE handles @help / @acehelp / @tele etc.
   server-side by intercepting Talk text with @ prefix; the user's
   message isn't broadcast and ACE replies via SystemChat. Drop the
   optimistic /say echo so the chat shows only the server's response
   (the SystemChat wiring from #1 surfaces it as [System] {help}).

Tests:
- 11 long-form-alias Theory cases on ChatInputParser.
- 3 own-guid-substitution cases on ChatLog (own match, different
  guid, pre-login fallback).
- Existing PrefixSubstring test refactored to "/genio" since the
  previous "/general" stub is now a real verb.

Solution total: 1021 green (243 Core.Net + 125 UI + 653 Core),
0 warnings, 0 errors. +14 tests.

Acceptance: at login, [System] Welcome to Asheron's Call appears.
Single "You say, \"hi\"" per /say. /allegiance with no allegiance
shows [Allegiance] You say, ... + [System] You are not in an
allegiance!. /patron / /vassals / /monarch route correctly.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -1254,6 +1254,24 @@ public sealed class GameWindow : IDisposable
             // Phase I.6: feed inbound TurbineChat events into the chat log.
             // The Response variant is fire-and-forget (server-side ack);
             // EventSendToRoom is a real chat message broadcast to a room.
+            // Phase J: ACE's GameMessageSystemChat (used for the login
+            // banner "Welcome to Asheron's Call ... type @acehelp" and
+            // for SystemChat broadcasts) rides opcode 0xF7E0 ServerMessage,
+            // parsed in I.5 but never wired. Surface it as a System
+            // chat line so the welcome banner appears + future server
+            // pushes (announcements, command responses) show.
+            _liveSession.ServerMessageReceived += sm =>
+                Chat.OnSystemMessage(sm.Message, sm.ChatType);
+
+            // Phase I.5 + J: emotes already had ChatLog adapters; wire
+            // their session events here so they actually reach chat.
+            _liveSession.EmoteHeard += emote =>
+                Chat.OnEmote(emote.SenderName, emote.Text, emote.SenderGuid);
+            _liveSession.SoulEmoteHeard += emote =>
+                Chat.OnSoulEmote(emote.SenderName, emote.Text, emote.SenderGuid);
+            _liveSession.PlayerKilledReceived += pk =>
+                Chat.OnPlayerKilled(pk.DeathMessage, pk.VictimGuid, pk.KillerGuid);
+
             _liveSession.TurbineChatReceived += parsed =>
             {
                 if (parsed.Body is AcDream.Core.Net.Messages.TurbineChat.Payload.EventSendToRoom ev)
@@ -1292,8 +1310,15 @@ public sealed class GameWindow : IDisposable
                 switch (cmd.Channel)
                 {
                     case AcDream.UI.Abstractions.ChatChannelKind.Say:
+                        // Phase J: drop optimistic /say echo. ACE's
+                        // HandleActionTalk broadcasts a HearSpeech back
+                        // to the sender too, and ChatLog.OnLocalSpeech
+                        // detects own-guid match to render it as
+                        // "You say, ...". Optimistic-echoing here
+                        // doubled the line. ALSO: don't echo "@xxx"
+                        // server-side admin commands — ACE consumes
+                        // them silently and replies via SystemChat.
                         liveSession.SendTalk(cmd.Text);
-                        chat.OnSelfSent(AcDream.Core.Chat.ChatKind.LocalSpeech, cmd.Text);
                         break;
                     case AcDream.UI.Abstractions.ChatChannelKind.Tell:
                         if (string.IsNullOrEmpty(cmd.TargetName)) return;
@@ -1398,6 +1423,7 @@ public sealed class GameWindow : IDisposable
             var chosen = _liveSession.Characters.Characters[0];
             _playerServerGuid = chosen.Id;  // Phase B.2: store for Tab-key player-mode entry
             _vitalsVm?.SetLocalPlayerGuid(chosen.Id);  // Phase D.2a — devtools HP bar tracks this guid
+            Chat.SetLocalPlayerGuid(chosen.Id);  // Phase J — recognize own /say echo from ACE's HearSpeech broadcast
             _worldState.MarkPersistent(chosen.Id);  // player entity survives landblock unloads
             Console.WriteLine($"live: entering world as 0x{chosen.Id:X8} {chosen.Name}");
             _liveSession.EnterWorld(user, characterIndex: 0);