feat(rank-battle): RankBattleController shell + DTOs + routing smoke tests

Stands up the controller with all 13 rank-battle URL routes wired via
explicit absolute [HttpPost] attributes (multi-prefix family — can't ride
[Route(\"[controller]\")]). Real DoMatching / AiStart logic arrives in
later tasks; finish + telemetry + force-finish are returnable stubs as
of this task.

DTOs cover the request + response shapes per the spec. Note the
camelCase wire keys on AiBattlePlayerInfo (sleeveId, emblemId, ...) —
the AI battle subsystem uses camelCase, not the project-default
snake_case, per AIBattleStartTask.Parse's literal Keys.Contains lookups.

DoMatchingResponseDto.NodeServerUrl is non-nullable + always-emit (with
[JsonIgnore(Never)]) — matches Phase 2's TK2 fix because the client's
DoMatchingBase parser calls .ToString() without a Keys.Contains guard.

13 routing smoke tests confirm each URL resolves to the controller.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/RankBattle/DoMatchingRequestDto.cs

@@ -0,0 +1,36 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.RankBattle;
+
+[MessagePackObject(keyAsPropertyName: true)]
+public sealed class DoMatchingRequestDto
+{
+    [JsonPropertyName("deck_no")]
+    [Key("deck_no")]
+    public int DeckNo { get; set; }
+
+    [JsonPropertyName("need_init")]
+    [Key("need_init")]
+    public int NeedInit { get; set; }
+
+    [JsonPropertyName("card_master_hash")]
+    [Key("card_master_hash")]
+    public string? CardMasterHash { get; set; }
+
+    [JsonPropertyName("log")]
+    [Key("log")]
+    public string? Log { get; set; }
+
+    [JsonPropertyName("use_stage_select")]
+    [Key("use_stage_select")]
+    public int UseStageSelect { get; set; }
+
+    [JsonPropertyName("excluded_field_id_list")]
+    [Key("excluded_field_id_list")]
+    public int[]? ExcludedFieldIdList { get; set; }
+
+    [JsonPropertyName("is_default_skin")]
+    [Key("is_default_skin")]
+    public int IsDefaultSkin { get; set; }
+}