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.EmulatedEntrypoint/Controllers/ArenaTwoPickBattleController.cs

@@ -1,5 +1,9 @@
 using Microsoft.AspNetCore.Mvc;
 using SVSim.BattleNode.Bridge;
+using SVSim.Database.Enums;
+using SVSim.Database.Services.Friend;
+using SVSim.Database.Services.Replay;
+using SVSim.EmulatedEntrypoint.Extensions;
 using SVSim.EmulatedEntrypoint.Matching;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.ArenaTwoPick;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
@@ -13,15 +17,24 @@ public class ArenaTwoPickBattleController : SVSimController
     private readonly IArenaTwoPickService _svc;
     private readonly IMatchContextBuilder _matchContextBuilder;
     private readonly IMatchingResolver _resolver;
+    private readonly IBattleContextStore _battleContextStore;
+    private readonly IBattleHistoryWriter _historyWriter;
+    private readonly IPlayedTogetherWriter _playedTogetherWriter;
 
     public ArenaTwoPickBattleController(
         IArenaTwoPickService svc,
         IMatchContextBuilder matchContextBuilder,
-        IMatchingResolver resolver)
+        IMatchingResolver resolver,
+        IBattleContextStore battleContextStore,
+        IBattleHistoryWriter historyWriter,
+        IPlayedTogetherWriter playedTogetherWriter)
     {
         _svc = svc;
         _matchContextBuilder = matchContextBuilder;
         _resolver = resolver;
+        _battleContextStore = battleContextStore;
+        _historyWriter = historyWriter;
+        _playedTogetherWriter = playedTogetherWriter;
     }
 
     [HttpPost("do_matching")]
@@ -34,6 +47,38 @@ public class ArenaTwoPickBattleController : SVSimController
         {
             var ctx = await _matchContextBuilder.BuildForTwoPickAsync(vid);
             var r = await _resolver.ResolveAsync("arena_two_pick_battle", new BattlePlayer(vid, ctx), ct);
+
+            if (r.BattleId is not null && long.TryParse(r.BattleId, out var battleIdLong))
+            {
+                _battleContextStore.Set(vid, new BattleContext(
+                    BattleId:           battleIdLong,
+                    // Two-pick wire battle_type — see docs/api-spec/common/types.ts.md
+                    // #battle-types. Captured prod frames use 4 for both private match
+                    // AND arena two-pick contexts; if a future capture disagrees, refine.
+                    BattleType:         4,
+                    DeckFormat:         Format.TwoPick.ToApi(),  // wire-int 10
+                    TwoPickType:        0,                       // captured "0"; refine once tracked on MatchContext
+                    SelfClassId:        (int)ctx.ClassId,        // CardClass enum
+                    SelfSubClassId:     0,
+                    SelfCharaId:        int.TryParse(ctx.CharaId, out var ch) ? ch : 0,
+                    SelfRotationId:     "0",
+                    // MatchContext (SVSim.BattleNode/Bridge/MatchContext.cs) does NOT carry
+                    // opponent identity — the resolver returns only the BattleId. Leave
+                    // opponent placeholders; when the two-pick matchmaking flow plumbs the
+                    // second player's MatchContext through to the resolver result, fill
+                    // these from there (and stash for both players).
+                    OpponentViewerId:   0,
+                    OpponentName:       "",
+                    OpponentClassId:    0,
+                    OpponentSubClassId: 0,
+                    OpponentCharaId:    0,
+                    OpponentCountryCode: "",
+                    OpponentEmblemId:   0,
+                    OpponentDegreeId:   0,
+                    OpponentRotationId: "0",
+                    BattleStartTime:    DateTime.UtcNow));
+            }
+
             return Ok(new DoMatchingResponseDto
             {
                 MatchingState = r.MatchingState,
@@ -48,12 +93,30 @@ public class ArenaTwoPickBattleController : SVSimController
     }
 
     [HttpPost("finish")]
-    public async Task<IActionResult> Finish([FromBody] BattleFinishRequest req)
+    public async Task<IActionResult> Finish([FromBody] BattleFinishRequest req, CancellationToken ct = default)
     {
         if (!TryGetViewerId(out var vid)) return Unauthorized();
         try
         {
-            var result = await _svc.RecordBattleResultAsync(vid, req.BattleResult == 1);
+            var battleCtx = _battleContextStore.TakeFor(vid);
+            bool isWin = req.BattleResult == 1;
+
+            await _historyWriter.RecordAsync(vid, battleCtx, isWin, ct);
+
+            if (battleCtx is { OpponentViewerId: > 0 })
+            {
+                await _playedTogetherWriter.RecordAsync(
+                    vid,
+                    battleCtx.OpponentViewerId,
+                    new BattleParticipationContext(
+                        PlayedMode: 0,
+                        BattleType: battleCtx.BattleType,
+                        DeckFormat: battleCtx.DeckFormat,
+                        TwoPickType: battleCtx.TwoPickType),
+                    ct);
+            }
+
+            var result = await _svc.RecordBattleResultAsync(vid, isWin);
             return Ok(new BattleFinishResponseDto
             {
                 BattleResult = result.BattleResult,