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/GuildChatPostResponse.cs

@@ -0,0 +1,22 @@
+using MessagePack;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.GuildChat;
+
+/// <summary>
+/// Response for POST /guild_chat/post.
+/// achieved_info and reward_list are optional; only present when posting triggered a mission completion.
+/// TODO(task-16): populate achieved_info + reward_list shapes when chat missions are implemented.
+/// </summary>
+[MessagePackObject]
+public class GuildChatPostResponse
+{
+    /// <summary>Optional. Present when posting triggered a mission completion.</summary>
+    [JsonPropertyName("achieved_info"), Key("achieved_info")]
+    public JsonElement? AchievedInfo { get; set; }
+
+    /// <summary>Optional. Goods deltas from any rewards in achieved_info.</summary>
+    [JsonPropertyName("reward_list"), Key("reward_list")]
+    public JsonElement? RewardList { get; set; }
+}