feat(guild): controller scaffolding + /guild/info baseline

- 5 common DTOs under Models/Dtos/Common/Guild/ (GuildDetailDto,
  GuildUserBaseDto, GuildMemberInfoDto, ChatUserDto, ChatMessageDto)
- 28 per-endpoint request/response DTOs under Models/Dtos/Guild/ and
  Models/Dtos/GuildChat/ with full [MessagePackObject]/[Key]/
  [JsonPropertyName] attribute mirrors on every property
- GuildController (22 actions): /guild/info returns prod-shape with
  config-backed max_member_num/max_sub_leader_num/usable_stamp_list;
  21 stubs return empty/default DTOs
- GuildChatController (7 stubs), /guild_chat/messages stub returns
  wait_interval=10 per config
- 29 new routing smoke test cases (100 total, all pass)
- GuildWireShape literal-JSON test for GuildInfoResponse (1/1 pass)
- GameConfigurationJsonbTests updated for 17th GuildConfig section
- Total: 1422 tests pass, 0 errors

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/Common/Guild/ChatMessageDto.cs

@@ -0,0 +1,54 @@
+using MessagePack;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Common.Guild;
+
+/// <summary>
+/// Wire shape for a single chat message in /guild_chat/messages `chat_message[]`
+/// and /gathering_chat/messages. Matches guild_chat-messages.md ChatMessage interface.
+///
+/// deck / replay / room are JsonElement? so arbitrary payloads can pass through in Phase 5
+/// without premature typing (TODO task-17: replace with typed DTOs when replay subsystem is documented).
+/// </summary>
+[MessagePackObject]
+public class ChatMessageDto
+{
+    [JsonPropertyName("viewer_id"), Key("viewer_id"), JsonConverter(typeof(StringifiedLongConverter))]
+    public long ViewerId { get; set; }
+
+    [JsonPropertyName("message_id"), Key("message_id"), JsonConverter(typeof(StringifiedLongConverter))]
+    public long MessageId { get; set; }
+
+    /// <summary>eMessageType: 0=NORMAL 1=STAMP 2=DECK 3=JOIN 4=LEAVE 5=REPLAY etc.</summary>
+    [JsonPropertyName("message_type"), Key("message_type"), JsonConverter(typeof(StringifiedIntConverter))]
+    public int MessageType { get; set; }
+
+    [JsonPropertyName("create_time"), Key("create_time"), JsonConverter(typeof(StringifiedLongConverter))]
+    public long CreateTime { get; set; }
+
+    /// <summary>Text body for NORMAL, stringified stamp id for STAMP, etc.</summary>
+    [JsonPropertyName("message"), Key("message")]
+    public string Message { get; set; } = "";
+
+    /// <summary>Present when message_type = DECK (2). Inline DeckLogData payload.</summary>
+    [JsonPropertyName("deck"), Key("deck")]
+    public JsonElement? Deck { get; set; }
+
+    /// <summary>Present when message_type = REPLAY (5). Inline ReplayInfoItem payload.</summary>
+    [JsonPropertyName("replay"), Key("replay")]
+    public JsonElement? Replay { get; set; }
+
+    /// <summary>Present when message_type = ROOM_MATCH (10). Inline room-invite payload.</summary>
+    [JsonPropertyName("room"), Key("room")]
+    public JsonElement? Room { get; set; }
+
+    /// <summary>GATHERING_TOURNAMENT_ROOM extras — only meaningful for /gathering_chat.</summary>
+    [JsonPropertyName("viewer_id1"), Key("viewer_id1")]
+    public long? ViewerId1 { get; set; }
+
+    /// <summary>GATHERING_TOURNAMENT_ROOM extras — only meaningful for /gathering_chat.</summary>
+    [JsonPropertyName("viewer_id2"), Key("viewer_id2")]
+    public long? ViewerId2 { get; set; }
+}