feat(replay): wire arena two-pick finish hook

Same pattern as rank-battle: DoMatching stashes context; Finish takes
it and records history + played-together. Opponent identity is left
as placeholder fields until the resolver carries it through.

Test seeds an active ViewerArenaTwoPickRun so RecordBattleResultAsync
does not throw no_active_run during the e2e flow.

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

SVSim.UnitTests/Controllers/ReplayControllerTests.cs

@@ -173,6 +173,59 @@ public class ReplayControllerTests
         Assert.That(infoBody!.ReplayList, Is.Empty);
     }
 
+    [Test]
+    public async Task ArenaTwoPickFinish_writes_history_row_visible_from_ReplayInfo()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync(steamId: 76_561_198_000_000_001UL);
+
+        // Seed an active arena run so RecordBattleResultAsync doesn't throw no_active_run.
+        using (var scope = factory.Services.CreateScope())
+        {
+            var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+            db.Set<ViewerArenaTwoPickRun>().Add(new ViewerArenaTwoPickRun
+            {
+                ViewerId = viewerId,
+                EntryId = 1,
+                ClassId = 1,
+                MaxBattleCount = 5,
+                WinCount = 0,
+                LossCount = 0,
+                ResultListJson = "[]",
+                CreatedAt = DateTime.UtcNow,
+                UpdatedAt = DateTime.UtcNow,
+            });
+            await db.SaveChangesAsync();
+        }
+
+        var store = factory.Services.GetRequiredService<IBattleContextStore>();
+        store.Set(viewerId, new BattleContext(
+            BattleId: 999_888_777L,
+            BattleType: 4, DeckFormat: 10, TwoPickType: 0,
+            SelfClassId: 1, SelfSubClassId: 0, SelfCharaId: 1, SelfRotationId: "0",
+            OpponentViewerId: 0, OpponentName: "TwoPickBot", OpponentClassId: 2,
+            OpponentSubClassId: 0, OpponentCharaId: 1, OpponentCountryCode: "",
+            OpponentEmblemId: 0, OpponentDegreeId: 0, OpponentRotationId: "0",
+            BattleStartTime: DateTime.UtcNow));
+
+        var client = factory.CreateAuthenticatedClient(viewerId);
+
+        var finishResp = await client.PostAsJsonAsync("/arena_two_pick_battle/finish", new
+        {
+            viewer_id = "0",
+            steam_id = 0,
+            steam_session_ticket = "",
+            battle_result = 1,
+        });
+        Assert.That(finishResp.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        var infoBody = await client.PostAsJsonAsync("/replay/info", EmptyBody())
+            .ContinueWith(t => t.Result.Content.ReadFromJsonAsync<ReplayInfoResponseDto>())
+            .Unwrap();
+        Assert.That(infoBody!.ReplayList, Has.Count.EqualTo(1));
+        Assert.That(infoBody.ReplayList[0].OpponentName, Is.EqualTo("TwoPickBot"));
+    }
+
     private static ViewerBattleHistory NewRow(long viewerId, long battleId, DateTime createTime) => new()
     {
         ViewerId = viewerId,