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/ArenaTwoPickBattleController.cs

@@ -128,6 +128,11 @@ public class ArenaTwoPickBattleController : SVSimController
                 vid,
                 isWin ? MissionEventKeys.Challenge.MatchWinAll() : MissionEventKeys.Challenge.MatchPlayAll(),
                 ct: ct);
+            if (result.LeveledUp)
+            {
+                await _missionProgress.RecordEventAsync(
+                    vid, MissionEventKeys.ClassLevel.UpAll(result.ClassId), ct: ct);
+            }
 
             return Ok(new BattleFinishResponseDto
             {