feat(battle-xp): wire free-battle /finish through IBattleXpService

- FreeBattleController.Finish (rotation + unlimited URLs) now grants
  win/loss XP via IBattleXpService with BattleXpMode.Free.
- Preserves the strict field subset (no rank/master fields).
- Tests updated: win asserts XP+level-up; new loss test on rotation URL.

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

SVSim.EmulatedEntrypoint/Controllers/FreeBattleController.cs

@@ -1,7 +1,10 @@
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using SVSim.BattleNode.Bridge;
+using SVSim.Database;
 using SVSim.Database.Enums;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.Database.Services.BattleXp;
 using SVSim.Database.Services.Friend;
 using SVSim.Database.Services.Replay;
 using SVSim.EmulatedEntrypoint.Constants;
@@ -32,6 +35,9 @@ public sealed class FreeBattleController : ControllerBase
     private readonly IBattleContextStore _battleContextStore;
     private readonly IBattleHistoryWriter _historyWriter;
     private readonly IPlayedTogetherWriter _playedTogetherWriter;
+    private readonly IViewerRepository _viewers;
+    private readonly IBattleXpService _xp;
+    private readonly SVSimDbContext _db;
     private readonly ILogger<FreeBattleController> _log;
 
     public FreeBattleController(
@@ -40,6 +46,9 @@ public sealed class FreeBattleController : ControllerBase
         IBattleContextStore battleContextStore,
         IBattleHistoryWriter historyWriter,
         IPlayedTogetherWriter playedTogetherWriter,
+        IViewerRepository viewers,
+        IBattleXpService xp,
+        SVSimDbContext db,
         ILogger<FreeBattleController> log)
     {
         _resolver = resolver;
@@ -47,6 +56,9 @@ public sealed class FreeBattleController : ControllerBase
         _battleContextStore = battleContextStore;
         _historyWriter = historyWriter;
         _playedTogetherWriter = playedTogetherWriter;
+        _viewers = viewers;
+        _xp = xp;
+        _db = db;
         _log = log;
     }
 
@@ -97,10 +109,23 @@ public sealed class FreeBattleController : ControllerBase
                 ct);
         }
 
+        int gainXp = 0, totalXp = 0, level = 1;
+        var viewer = await _viewers.LoadForBattleXpGrantAsync(vid, ct);
+        if (viewer is not null)
+        {
+            var xp = await _xp.GrantAsync(viewer, req.ClassId, isWin, BattleXpMode.Free, ct);
+            await _db.SaveChangesAsync(ct);
+            gainXp = xp.GetXp;
+            totalXp = xp.TotalXp;
+            level = xp.Level == 0 ? 1 : xp.Level;
+        }
+
         return Ok(new FreeBattleFinishResponseDto
         {
             BattleResult = req.BattleResult,
-            // All other fields default to 0 (ClassLevel defaults to 1).
+            GetClassExperience = gainXp,
+            ClassExperience = totalXp,
+            ClassLevel = level,
         });
     }