fix: 12h cooldown before reopening manually closed host_silence (0.9.9)

Track resolved_by on problems; suppress scan/ingest recreate after manual
resolve; reopen same problem after cooldown; auto-close via heartbeat unchanged.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/config.py

@@ -88,6 +88,8 @@ class Settings(BaseSettings):
     # Периодическое сканирование stale heartbeat (proactive host_silence)
     sac_host_silence_scan_enabled: bool = True
     sac_host_silence_scan_interval_minutes: int = 5
+    # После ручного закрытия host_silence не открывать снова раньше N часов (auto-close по heartbeat — без паузы).
+    sac_host_silence_manual_resolve_cooldown_hours: int = 12
 
     # Окно корреляции Problems: host + type + rule в одном open Problem
     sac_problem_correlation_window_minutes: int = 60