feat(arena-colosseum): lobby + constructed entry (phase 1)

Closes 5 of arena-colosseum's 16 spec shapes (1/16 → 6/16). Lobby reads
(/top, /get_fee_info, /event_info) render an empty "no event scheduled"
payload by default; /entry + /register_deck activate via admin-flipped
ColosseumSeason + ColosseumRounds config sections.

* Schema: ViewerArenaColosseumRun standalone table (unique on ViewerId)
  with jsonb run-state columns mirroring ViewerArenaTwoPickRun.
* Config sections: ColosseumSeasonConfig (event-level), ColosseumRoundsConfig
  (the 3-round bracket). Empty defaults — IsColosseumPeriod=false.
* Migration AddArenaColosseumRun (DDL only; seed rows come from the section
  ShippedDefaults via EnsureSeedDataAsync).
* DTOs: ColosseumLobbyInfo (round-level, /top + /get_fee_info), ColosseumEventInfo
  (event-level, /event_info), ColosseumOwnStatus (shared status block),
  ColosseumEntryRef, ColosseumFeeList, ColosseumUserDeck, ColosseumBattleResults,
  ColosseumRoundDetail + ColosseumGroupRow. EventInfoResponse uses explicit
  [JsonPropertyName("1"|"2"|"3")] for the string-keyed rounds shape per spec.
* Controller: ArenaColosseumController replaces the 1-action stub with
  the five lifecycle endpoints. /top emits leader_skin_id even when 0
  (project_wire_null_policy override).
* Tests: 11 controller-level tests + 6 config round-trip tests covering
  empty-season payloads, run-seeded /top round-trip, crystal/rupy entry
  debits, now_round_id mismatch rejection, deck_no_list round-trip + reject.

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaColosseum/EntryResponse.cs

@@ -0,0 +1,22 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /arena_colosseum/entry</c>. Sparse — only <c>reward_list</c> (wallet debit) +
+/// <c>entry_info.deck_format</c>. Client refreshes full lobby state via the next <c>/top</c>.
+/// Reuses <see cref="RewardEntryDto"/> from arena-two-pick — the wire shape is identical
+/// (<c>reward_type/reward_id/reward_num</c> per <c>UpdateHaveUserGoodsNumByJsonData</c>).
+/// </summary>
+[MessagePackObject]
+public class EntryResponse
+{
+    [JsonPropertyName("reward_list")] [Key("reward_list")]
+    public List<RewardEntryDto> RewardList { get; set; } = new();
+
+    [JsonPropertyName("entry_info")] [Key("entry_info")]
+    public ColosseumEntryRef EntryInfo { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaColosseum/EventInfoResponse.cs

@@ -0,0 +1,31 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /arena_colosseum/event_info</c>. The 3-round Colosseum bracket descriptor — note
+/// the rounds are STRING-keyed (<c>"1"</c>, <c>"2"</c>, <c>"3"</c>), NOT an array. The
+/// client iterates <c>for (i = 1; i &lt;= 3; i++) jsonData[i.ToString()]</c>. Using three
+/// explicit <c>[JsonPropertyName("1"|"2"|"3")]</c> properties is simpler than a custom STJ
+/// converter and round-trips cleanly through MessagePack via matching <c>[Key("1"|...)]</c>.
+/// </summary>
+[MessagePackObject]
+public class EventInfoResponse
+{
+    [JsonPropertyName("colosseum_info")] [Key("colosseum_info")]
+    public ColosseumEventInfo ColosseumInfo { get; set; } = new();
+
+    [JsonPropertyName("1")] [Key("1")]
+    public ColosseumRoundDetail Round1 { get; set; } = new();
+
+    [JsonPropertyName("2")] [Key("2")]
+    public ColosseumRoundDetail Round2 { get; set; } = new();
+
+    [JsonPropertyName("3")] [Key("3")]
+    public ColosseumRoundDetail Round3 { get; set; } = new();
+
+    [JsonPropertyName("colosseum_status")] [Key("colosseum_status")]
+    public ColosseumOwnStatus ColosseumStatus { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaColosseum/GetFeeInfoResponseDto.cs

@@ -1,39 +1,46 @@
 using System.Text.Json.Serialization;
 using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
 
 namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
 
 /// <summary>
-/// Minimum-viable stub for /arena_colosseum/get_fee_info — emits is_colosseum_period:false
-/// so the client (Wizard/ColosseumEntryInfoTask.cs:99) skips the rest of the parse and the
-/// home/arena screen renders without 404ing. TODO: implement the full Colosseum entry flow
-/// when the Colosseum format is brought online.
+/// <c>POST /arena_colosseum/get_fee_info</c> — pre-entry oracle. Most fields are optional;
+/// presence drives the lobby state machine on the client side
+/// (<c>Wizard/ColosseumEntryInfoTask.cs</c>). When no season is active, only
+/// <see cref="ColosseumInfo"/> + <see cref="ColosseumStatus"/> are emitted (the former with
+/// <c>is_colosseum_period:false</c>, the latter as <c>{}</c> via WhenWritingNull stripping).
 /// </summary>
 [MessagePackObject]
 public class GetFeeInfoResponseDto
 {
-    /// <summary>
-    /// Per-viewer Colosseum entry status (rest_entry_num, now_round_id, is_last_day, etc.).
-    /// Empty object — client (ColosseumEntryInfoTask.cs:146) guards with `if (status.Count != 0)`,
-    /// so an empty dict short-circuits cleanly.
-    /// </summary>
-    [JsonPropertyName("colosseum_status")] [Key("colosseum_status")]
-    public ColosseumStatusDto ColosseumStatus { get; set; } = new();
-
     [JsonPropertyName("colosseum_info")] [Key("colosseum_info")]
-    public ColosseumInfoDto ColosseumInfo { get; set; } = new();
-}
+    public ColosseumLobbyInfo ColosseumInfo { get; set; } = new();
 
-[MessagePackObject]
-public class ColosseumStatusDto { }
+    [JsonPropertyName("colosseum_status")] [Key("colosseum_status")]
+    public ColosseumOwnStatus ColosseumStatus { get; set; } = new();
 
-[MessagePackObject]
-public class ColosseumInfoDto
-{
-    /// <summary>
-    /// false = no Colosseum event running. Client (ColosseumEntryInfoTask.cs:100) gates every
-    /// other field on this — emitting false is what lets us ship an otherwise-empty info block.
-    /// </summary>
-    [JsonPropertyName("is_colosseum_period")] [Key("is_colosseum_period")]
-    public bool IsColosseumPeriod { get; set; } = false;
+    [JsonPropertyName("is_unfinished_entry_exists")] [Key("is_unfinished_entry_exists")]
+    public bool? IsUnfinishedEntryExists { get; set; }
+
+    [JsonPropertyName("is_allowed_free_entry")] [Key("is_allowed_free_entry")]
+    public bool? IsAllowedFreeEntry { get; set; }
+
+    [JsonPropertyName("fee_list")] [Key("fee_list")]
+    public ColosseumFeeList? FeeList { get; set; }
+
+    [JsonPropertyName("deck_format")] [Key("deck_format")]
+    public int? DeckFormat { get; set; }
+
+    [JsonPropertyName("is_able_to_join_round_3")] [Key("is_able_to_join_round_3")]
+    public bool? IsAbleToJoinRound3 { get; set; }
+
+    [JsonPropertyName("is_already_entry_final_round")] [Key("is_already_entry_final_round")]
+    public bool? IsAlreadyEntryFinalRound { get; set; }
+
+    [JsonPropertyName("is_deck_deleted")] [Key("is_deck_deleted")]
+    public bool? IsDeckDeleted { get; set; }
+
+    [JsonPropertyName("two_pick_status")] [Key("two_pick_status")]
+    public int? TwoPickStatus { get; set; }
 }

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaColosseum/TopResponse.cs

@@ -0,0 +1,61 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /arena_colosseum/top</c> — lobby state for an in-progress run. When no season is
+/// active <see cref="ColosseumInfo.IsColosseumPeriod"/> is <c>false</c> and most other
+/// fields are absent (the client guards on that flag before reading anything else).
+/// </summary>
+[MessagePackObject]
+public class TopResponse
+{
+    [JsonPropertyName("entry_info")] [Key("entry_info")]
+    public ColosseumEntryRef EntryInfo { get; set; } = new();
+
+    [JsonPropertyName("colosseum_info")] [Key("colosseum_info")]
+    public ColosseumLobbyInfo ColosseumInfo { get; set; } = new();
+
+    [JsonPropertyName("colosseum_status")] [Key("colosseum_status")]
+    public ColosseumOwnStatus ColosseumStatus { get; set; } = new();
+
+    [JsonPropertyName("now_round_id")] [Key("now_round_id")]
+    public int NowRoundId { get; set; }
+
+    [JsonPropertyName("user_deck")] [Key("user_deck")]
+    public List<ColosseumUserDeck> UserDeck { get; set; } = new();
+
+    [JsonPropertyName("max_battle_count")] [Key("max_battle_count")]
+    public int MaxBattleCount { get; set; }
+
+    [JsonPropertyName("is_finish")] [Key("is_finish")]
+    public bool IsFinish { get; set; }
+
+    [JsonPropertyName("final_round_eliminate_count")] [Key("final_round_eliminate_count")]
+    public int FinalRoundEliminateCount { get; set; }
+
+    [JsonPropertyName("end_time")] [Key("end_time")]
+    public string EndTime { get; set; } = "";
+
+    [JsonPropertyName("battle_results")] [Key("battle_results")]
+    public ColosseumBattleResults BattleResults { get; set; } = new();
+
+    [JsonPropertyName("breakthrough_number")] [Key("breakthrough_number")]
+    public int? BreakthroughNumber { get; set; }
+
+    [JsonPropertyName("box_grade_list")] [Key("box_grade_list")]
+    public List<int>? BoxGradeList { get; set; }
+
+    [JsonPropertyName("selected_chaos_id")] [Key("selected_chaos_id")]
+    public int? SelectedChaosId { get; set; }
+
+    /// <summary>ALWAYS emitted, even when 0. <c>WhenWritingNull</c> would strip this otherwise —
+    /// see <c>project_wire_null_policy</c>: client does <c>jsonData["leader_skin_id"].ToInt()</c>
+    /// unguarded, which throws a KeyNotFoundException if absent.</summary>
+    [JsonPropertyName("leader_skin_id")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.Never)]
+    [Key("leader_skin_id")]
+    public long LeaderSkinId { get; set; }
+}