fix(server): mark games abandoned on room teardown + staging leaderboard

When handle_player_leave emptied a room or handle_end_game was invoked,
the room was removed from memory without touching games_v2. Periodic
cleanup only scans in-memory rooms, so those rows were stranded as
status='active' forever — staging had 42 orphans accumulated over 5h.

- event_store.update_game_abandoned: guarded UPDATE (status='active' only)
- GameLogger.log_game_abandoned{,_async}: fire-and-forget wrapper
- handle_end_game + handle_player_leave: flip status before remove_room
- LEADERBOARD_INCLUDE_TEST_DEFAULT: env override so staging can show
  soak-harness accounts by default; prod keeps them hidden

Verified on staging: 42 orphans swept on restart, soak accounts now
visible on /api/stats/leaderboard (rank 1-4).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/routers/stats.py

@@ -12,6 +12,7 @@ from typing import Optional
 from fastapi import APIRouter, Depends, HTTPException, Header, Query
 from pydantic import BaseModel
 
+from config import config
 from models.user import User
 from services.stats_service import StatsService
 
@@ -159,7 +160,7 @@ async def get_leaderboard(
     metric: str = Query("wins", pattern="^(wins|win_rate|avg_score|knockouts|streak|rating)$"),
     limit: int = Query(50, ge=1, le=100),
     offset: int = Query(0, ge=0),
-    include_test: bool = Query(False, description="Include soak-harness test accounts"),
+    include_test: Optional[bool] = Query(None, description="Include soak-harness test accounts. Defaults to LEADERBOARD_INCLUDE_TEST_DEFAULT env (False in prod)."),
     service: StatsService = Depends(get_stats_service_dep),
 ):
     """
@@ -173,9 +174,14 @@ async def get_leaderboard(
     - streak: Best win streak
 
     Players must have 5+ games to appear on leaderboards.
-    By default, soak-harness test accounts are hidden.
+    Soak-harness test accounts are hidden unless include_test is passed,
+    or LEADERBOARD_INCLUDE_TEST_DEFAULT is set True on the server (staging).
     """
-    entries = await service.get_leaderboard(metric, limit, offset, include_test)
+    effective_include_test = (
+        include_test if include_test is not None
+        else config.LEADERBOARD_INCLUDE_TEST_DEFAULT
+    )
+    entries = await service.get_leaderboard(metric, limit, offset, effective_include_test)
 
     return {
         "metric": metric,