stop infinite retry loop on rejected Lichess tokens

A gamer's periodic check would get permanently stuck if their stored token
was revoked/expired: our stats API collapsed both "Lichess rejected the
token" (401/403, permanent) and genuine transient errors into the same 502
response, so the bot treated an invalid token exactly like a network blip —
retrying the same window forever at a capped 300s backoff, never advancing
the checkpoint (observed in prod: Dor1zz stuck for 100+ consecutive errors
over 8+ hours, admin alerts firing every 25 failures).

Preserve the distinction that already existed one layer down (lichess_client.py
already tells 401/403 apart from other failures) instead of collapsing it in
stats_service.py: add PuzzleOfPeriodResponse.auth_failed, have main.py return
401 specifically for that case, and have the bot raise a distinct
InvalidTokenError instead of returning None. On InvalidTokenError, the bot now
clears the token for that pair, notifies the user to reconnect via /addtoken,
and continues tracking games normally instead of stalling forever.

LichessClientTG_bot/i18n.py

@@ -72,7 +72,8 @@ TRANSLATIONS = {
         'user_not_found': "❌ Player {username} not found on Lichess. Check the spelling of the name.",
         'lichess_temporarily_unavailable': "⚠️ Lichess is temporarily unavailable. Please try again in a minute.",
         'gamer_already_added': "ℹ️ Player {username} is already being tracked.\n\nTo add another player, use /addgamer",
-        
+        'token_rejected_notice': "⚠️ Lichess rejected the saved token for {username} — puzzle stats have been turned off for this player, game tracking continues as normal. Use /addtoken to reconnect a fresh token if you want puzzle stats back.",
+
         # Get gamers
         'no_gamers': "📭 No players in database. Use /addgamer to add.",
         'loading_ratings': "🔄 Loading player ratings...",
@@ -215,7 +216,8 @@ TRANSLATIONS = {
         'user_not_found': "❌ Игрок {username} не найден на Lichess. Проверьте правильность написания имени.",
         'lichess_temporarily_unavailable': "⚠️ Lichess временно недоступен. Попробуйте, пожалуйста, через минуту.",
         'gamer_already_added': "ℹ️ Игрок {username} уже отслеживается.\n\nДля добавления следующего игрока воспользуйтесь /addgamer",
-        
+        'token_rejected_notice': "⚠️ Lichess отклонил сохранённый токен для {username} — статистика по пазлам для этого игрока отключена, отслеживание партий продолжается как обычно. Используйте /addtoken, чтобы подключить новый токен и вернуть статистику по пазлам.",
+
         # Get gamers
         'no_gamers': "📭 Нет игроков в базе данных. Используйте /addgamer для добавления.",
         'loading_ratings': "🔄 Загрузка рейтингов игроков...",