feat(arena-colosseum): playable bracket + rank-match promotion (phase 2)

Closes 4 more arena-colosseum spec shapes (6/16 → 10/16): the dual-prefix
battle URLs (colosseum_battle/* and colosseum_rank_battle/*) for both
do_matching and per-match finish, plus the bracket-end /finish + /retire
pair on /arena_colosseum.

* ColosseumProgressionService: pure-logic decisions for win-threshold
  advancement, 3008 promotion trigger, and per-round reward bundles.
  Extends ColosseumRoundsConfig with FinishRewards/RetireRewards per
  round + a top-level ChampionRewards list.
* MatchContextBuilder.BuildForColosseumAsync: lifts the registered deck
  via IDeckRepository (NOT viewer-graph) per project_ef_nav_include_pitfall.
* ArenaColosseumBattleController: dual route prefixes off one controller
  via explicit absolute [HttpPost("/...")] routes — does NOT extend
  SVSimController's [Route("[controller]")]. Same pattern as FreeBattle.
  URL-vs-IsRankMatching mismatch returns 400 with a phase-mismatch error;
  no-deck triggers the standard 3001 matchmaking-illegal state. 3008
  flips run.IsRankMatching exactly once via the progression service.
* /arena_colosseum/finish + /retire share FinishResponse (rewards +
  reward_list + colosseum_status). Champion finish appends ChampionRewards
  and surfaces colosseum_status.is_champion = true. Both delete the run
  row after granting via IInventoryTransaction.GrantAsync.
* DI: ModePolicy entries for "colosseum_battle" and "colosseum_rank_battle".
* Tests: 8 progression-service unit tests (pure logic), 5 battle-controller
  HTTP tests, 5 bracket-terminate HTTP tests, 2 full-bracket E2E walks
  (champion path + retire mid-round). Full suite: 1331/1331.

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/ColosseumReceivedReward.cs

@@ -0,0 +1,26 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// Per-entry shape for the <c>rewards</c> array on <c>/finish</c> + <c>/retire</c>. Richer
+/// than <c>RewardEntryDto</c> (which is the <c>reward_list</c> shape) — carries a display
+/// name. Distinct from the wallet-delta block: client renders <c>rewards</c> in the
+/// post-bracket popup while <c>reward_list</c> drives the silent wallet update.
+/// </summary>
+[MessagePackObject]
+public sealed class ColosseumReceivedReward
+{
+    [JsonPropertyName("reward_number")] [Key("reward_number")]
+    public int RewardNumber { get; set; }
+
+    [JsonPropertyName("reward_type")] [Key("reward_type")]
+    public int RewardType { get; set; }
+
+    [JsonPropertyName("reward_detail_id")] [Key("reward_detail_id")]
+    public long RewardDetailId { get; set; }
+
+    [JsonPropertyName("name")] [Key("name")]
+    public string Name { get; set; } = "";
+}