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/GuildChat/GuildChatPostRequest.cs

@@ -0,0 +1,26 @@
+using MessagePack;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.GuildChat;
+
+/// <summary>Request for POST /guild_chat/post. Posts a text message or stamp to guild chat.</summary>
+[MessagePackObject]
+public class GuildChatPostRequest
+{
+    [JsonPropertyName("viewer_id"), Key("viewer_id")]
+    public string ViewerId { get; set; } = "";
+
+    [JsonPropertyName("steam_id"), Key("steam_id")]
+    public ulong SteamId { get; set; }
+
+    [JsonPropertyName("steam_session_ticket"), Key("steam_session_ticket")]
+    public string SteamSessionTicket { get; set; } = "";
+
+    /// <summary>eMessageType: 0=NORMAL (text body), 1=STAMP (stringified stamp id).</summary>
+    [JsonPropertyName("type"), Key("type")]
+    public int Type { get; set; }
+
+    /// <summary>Text body for NORMAL; stringified stamp id for STAMP.</summary>
+    [JsonPropertyName("message"), Key("message")]
+    public string Message { get; set; } = "";
+}