feat(net): #18 holtburger inbound chat parity - EmoteText, SoulEmote, ServerMessage, PlayerKilled, WeenieError + Windows-1252 codec

Five sub-changes:

1. Windows-1252 codec switch (global). Every Encoding.ASCII call site
   in src/AcDream.Core.Net/Messages/ -> Encoding.GetEncoding(1252).
   Touched HearSpeech, ChatRequests, GameEvents, AppraiseInfoParser,
   CharacterList, CreateObject, PlayerDescriptionParser, SocialActions.
   New Encodings.cs module-init registers CodePagesEncodingProvider
   (System.Text.Encoding.CodePages ships with .NET 10 SDK but isn't
   auto-registered). Matches retail + holtburger; accented names
   no longer round-trip-broken.

2. New parsers (opcodes confirmed against holtburger opcodes.rs):
   - EmoteText (0x01E0)     { u32 senderGuid, string16 senderName, string16 text }
   - SoulEmote (0x01E2)     same wire layout as EmoteText
   - ServerMessage (0xF7E0) { string16 message, u32 chatType }
   - PlayerKilled (0x019E)  { string16 deathMessage, u32 victimGuid, u32 killerGuid }
   Shared StringReader.cs has the CP1252 String16L primitive.

3. WorldSession dispatch. ProcessDatagram adds branches for the four
   new top-level opcodes + fires session-level events (EmoteHeard,
   SoulEmoteHeard, ServerMessageReceived, PlayerKilledReceived).
   0x0295 SetTurbineChatChannels stubbed with TODO for parallel I.6.

4. GameEventWiring routes WeenieError + WeenieErrorWithString
   (parsers existed but were unrouted) -> chat.OnWeenieError.

5. ChatLog adapters: Emote / SoulEmote ChatKind values, OnEmote,
   OnSoulEmote, OnPlayerKilled, OnWeenieError. OnLocalSpeech now
   substitutes empty sender -> "You" per holtburger client/messages.rs.
   ChatVM.FormatEntry handles new kinds (asterisk + sender + text).

22 new tests covering parser round-trips + reject-bad-opcode +
ChatLog adapter coverage + Win-1252 round-trip with non-ASCII chars.
Solution total: 881 green (210->225 in Core.Net.Tests, 606->613 in Core.Tests).

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

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

@@ -90,4 +90,86 @@ public sealed class ChatLogTests
         log.Clear();
         Assert.Equal(0, log.Count);
     }
+
+    // ── Phase I.5: emote / soul-emote / killed / weenie-error adapters ──
+
+    [Fact]
+    public void OnEmote_AppendsEmoteEntry()
+    {
+        var log = new ChatLog();
+        log.OnEmote("Caith", "waves at you", 0xCAFE);
+        var e = log.Snapshot()[0];
+        Assert.Equal(ChatKind.Emote, e.Kind);
+        Assert.Equal("Caith", e.Sender);
+        Assert.Equal("waves at you", e.Text);
+        Assert.Equal(0xCAFEu, e.SenderGuid);
+    }
+
+    [Fact]
+    public void OnSoulEmote_AppendsSoulEmoteEntry()
+    {
+        var log = new ChatLog();
+        log.OnSoulEmote("Bob", "dances", 0xBEEF);
+        var e = log.Snapshot()[0];
+        Assert.Equal(ChatKind.SoulEmote, e.Kind);
+        Assert.Equal("Bob", e.Sender);
+        Assert.Equal("dances", e.Text);
+        Assert.Equal(0xBEEFu, e.SenderGuid);
+    }
+
+    [Fact]
+    public void OnPlayerKilled_AppendsSystemEntry_StoresGuids()
+    {
+        var log = new ChatLog();
+        log.OnPlayerKilled("Caith was killed by a Drudge.",
+            victimGuid: 0x12345678u, killerGuid: 0x90ABCDEFu);
+        var e = log.Snapshot()[0];
+        Assert.Equal(ChatKind.System, e.Kind);
+        Assert.Equal("Caith was killed by a Drudge.", e.Text);
+        Assert.Equal(0x12345678u, e.SenderGuid);
+        Assert.Equal(0x90ABCDEFu, e.ChannelId);   // killer guid stashed here
+    }
+
+    [Fact]
+    public void OnWeenieError_PlainCode_AppendsSystemEntry()
+    {
+        var log = new ChatLog();
+        log.OnWeenieError(errorId: 0x1234, param: null);
+        var e = log.Snapshot()[0];
+        Assert.Equal(ChatKind.System, e.Kind);
+        Assert.Contains("0x1234", e.Text);
+        Assert.Equal(0x1234u, e.ChannelId);
+    }
+
+    [Fact]
+    public void OnWeenieError_WithString_AppendsInterpolation()
+    {
+        var log = new ChatLog();
+        log.OnWeenieError(errorId: 0x5678, param: "Mana Stone");
+        var e = log.Snapshot()[0];
+        Assert.Equal(ChatKind.System, e.Kind);
+        Assert.Contains("Mana Stone", e.Text);
+    }
+
+    [Fact]
+    public void OnLocalSpeech_EmptySender_SubstitutesYou()
+    {
+        // Holtburger client/messages.rs lines 476-487 — empty sender
+        // means the player is the speaker (echo back of their own
+        // ranged shout). Substitute "You" so the chat line reads
+        // "You: hello" instead of ": hello".
+        var log = new ChatLog();
+        log.OnLocalSpeech(sender: "", text: "hello", senderGuid: 0, isRanged: false);
+        var e = log.Snapshot()[0];
+        Assert.Equal("You", e.Sender);
+        Assert.Equal("hello", e.Text);
+    }
+
+    [Fact]
+    public void OnLocalSpeech_NonEmptySender_KeepsAsIs()
+    {
+        var log = new ChatLog();
+        log.OnLocalSpeech(sender: "Alice", text: "hi", senderGuid: 0xAA, isRanged: false);
+        Assert.Equal("Alice", log.Snapshot()[0].Sender);
+    }
 }