feat(mission): wire class_level_up emits from every XP-granting controller

Every _xp.GrantAsync callsite now conditionally emits class_level_up:{class}
when the returned BattleXpGrantResult.LeveledUp is true. Six callsites total:

- PracticeController.Finish
- RankBattleController.FinishInternal
- FreeBattleController.Finish
- ArenaTwoPickBattleController.Finish (LeveledUp + ClassId routed via
  BattleFinishResultDto — controller-side signals, not on wire)
- ArenaColosseumBattleController (missed in the original wire-up survey;
  colosseum-battle XP now also fires the level-up event when applicable)
- StoryController.Finish (LeveledUp + ClassId routed via new
  StoryFinishOutcome wrapper, mirroring the TK2 RunFinishOutcome pattern)

Story's IStoryService.FinishAsync now returns StoryFinishOutcome instead of
FinishResponse directly. Test callsites updated to unwrap .Response.

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

SVSim.EmulatedEntrypoint/Controllers/StoryController.cs

@@ -71,7 +71,7 @@ public class StoryController : SVSimController
     public async Task<ActionResult<FinishResponse>> Finish(FinishRequest req)
     {
         if (!TryGetViewerId(out long vid)) return Unauthorized();
-        var result = await _service.FinishAsync(ResolveApiType(), req, vid);
+        var outcome = await _service.FinishAsync(ResolveApiType(), req, vid);
 
         // Emit story-chapter-finish events for mission/achievement progress.
         var apiType = ResolveApiType();
@@ -87,8 +87,13 @@ public class StoryController : SVSimController
             await _missionProgress.RecordEventAsync(
                 vid, MissionEventKeys.Story.ChapterFinishAll(prefix, req.StoryId));
         }
+        if (outcome.LeveledUp && outcome.ClassId.HasValue)
+        {
+            await _missionProgress.RecordEventAsync(
+                vid, MissionEventKeys.ClassLevel.UpAll(outcome.ClassId.Value));
+        }
 
-        return result;
+        return outcome.Response;
     }
 
     [HttpPost("/main_story/all_finish")]