fix: test push errors, skip heartbeat notify, stale 5h (0.9.2)

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

backend/app/config.py

@@ -83,7 +83,7 @@ class Settings(BaseSettings):
     sac_daily_report_require_activity: bool = True
 
     # Порог «живости» агента
-    sac_heartbeat_stale_minutes: int = 780
+    sac_heartbeat_stale_minutes: int = 300
 
     # Периодическое сканирование stale heartbeat (proactive host_silence)
     sac_host_silence_scan_enabled: bool = True