prioritize interactive requests over background checks in shared Lichess-token queue

/today, /yesterday, /week were queuing behind the entire periodic-check
backlog on the same rate-limited LICHESS_APP_TOKEN (observed ~2min wait on
prod for a single command). Add a two-tier priority queue to SharedTokenGate:
interactive on-demand requests jump ahead of background periodic checks,
which still drain normally when nothing interactive is waiting. Verified
locally end-to-end (isolated queue unit tests, live request with priority
correctly reaching Lichess, and a real successful accuracy fetch rendered
through StatsFormatter).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

LichessWebServices/main.py

@@ -503,7 +503,11 @@ async def get_games_of_period(
                             example=True),
     include_games: bool = Query(False,
                             description="Включить построчный список отдельных партий (только blitz/rapid/classical)",
-                            example=False)
+                            example=False),
+    priority: str = Query("background",
+                            pattern="^(background|interactive)$",
+                            description="\"interactive\" (запросы из /today и т.п.) обгоняет \"background\" (периодические проверки) в общей очереди shared-token запросов к Lichess",
+                            example="background")
 ):
     """
     ## Статистика игр за период
@@ -557,7 +561,7 @@ async def get_games_of_period(
         # Конвертируем миллисекунды в секунды для внутренней логики
         since_seconds = since // 1000
         until_seconds = until // 1000
-        result = await stats_service.get_games_of_period(username, since_seconds, until_seconds, rated_only, include_games)
+        result = await stats_service.get_games_of_period(username, since_seconds, until_seconds, rated_only, include_games, priority=priority)
         if not result.success:
             # Реальная ошибка при обращении к Lichess — не маскируем её под "0 игр"
             raise HTTPException(status_code=502, detail=result.message)