feat: external HTTPS monitoring pull via monitor.php

Add cron-ready pull checks for critical URLs with SSL expiry warnings,
retry-before-alert, JSON results in private/data, email alerts, and a
90-day target-list review reminder.

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

scripts/sync-server-env.py

@@ -16,6 +16,7 @@ SERVER_KEYS = [
     "SMTP_PASSWORD",
     "SMTP_FROM",
     "ALERT_EMAIL",
+    "TARGETS_REVIEW_INTERVAL_DAYS",
     "MONITOR_INGEST_TOKEN",
     "MONITOR_INGEST_URL",
     "TELEGRAM_BOT_TOKEN",