feat: Telegram notifications from SAC on ingest

Send Telegram alerts for high/critical events and new Problems.
Configurable via TELEGRAM_* env vars; ingest never fails on send errors.

backend/app/services/telegram_notify.py

@@ -0,0 +1,70 @@
+import logging
+
+import httpx
+
+from app.config import get_settings
+from app.models import Event, Problem
+
+logger = logging.getLogger(__name__)
+
+SEVERITY_ORDER = {"info": 10, "warning": 20, "high": 30, "critical": 40}
+
+
+def _severity_value(value: str) -> int:
+    return SEVERITY_ORDER.get(value, 0)
+
+
+def _is_enabled() -> bool:
+    settings = get_settings()
+    return bool(
+        settings.telegram_enabled
+        and settings.telegram_bot_token.strip()
+        and settings.telegram_chat_id.strip()
+    )
+
+
+def _send_text(message: str) -> None:
+    settings = get_settings()
+    if not _is_enabled():
+        return
+    url = f"https://api.telegram.org/bot{settings.telegram_bot_token}/sendMessage"
+    payload = {"chat_id": settings.telegram_chat_id, "text": message, "disable_web_page_preview": True}
+    try:
+        with httpx.Client(timeout=8.0) as client:
+            response = client.post(url, json=payload)
+            response.raise_for_status()
+    except Exception:
+        logger.exception("telegram send failed")
+
+
+def notify_event(event: Event) -> None:
+    settings = get_settings()
+    min_level = _severity_value(settings.telegram_min_severity)
+    if _severity_value(event.severity) < min_level:
+        return
+    host = event.host.hostname if event.host else "unknown"
+    message = (
+        f"🚨 SAC событие\n"
+        f"Host: {host}\n"
+        f"Severity: {event.severity}\n"
+        f"Type: {event.type}\n"
+        f"Title: {event.title}\n"
+        f"Summary: {event.summary}"
+    )
+    _send_text(message)
+
+
+def notify_problem(problem: Problem, event: Event | None = None) -> None:
+    host = problem.host.hostname if problem.host else "unknown"
+    related = ""
+    if event is not None:
+        related = f"\nEvent: {event.type} ({event.severity})"
+    message = (
+        f"🔥 SAC Problem opened\n"
+        f"Host: {host}\n"
+        f"Severity: {problem.severity}\n"
+        f"Rule: {problem.rule_id or '-'}\n"
+        f"Title: {problem.title}\n"
+        f"Summary: {problem.summary}{related}"
+    )
+    _send_text(message)