feat: SMTP email notification channel with UI and ingest

Migration 006, email config DB/env, smtplib sender, settings API,
Settings UI section, and dispatch on event/problem ingest.

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

backend/app/services/email_notify.py

@@ -0,0 +1,135 @@
+"""SMTP email notifications from SAC."""
+
+from __future__ import annotations
+
+import logging
+import re
+import smtplib
+from email.mime.text import MIMEText
+
+from sqlalchemy.orm import Session
+
+from app.models import Event, Problem
+from app.services.notification_settings import EmailConfig, get_effective_email_config
+from app.services.telegram_notify import SEVERITY_ORDER
+
+logger = logging.getLogger(__name__)
+
+
+class EmailNotConfiguredError(Exception):
+    """Email disabled or missing SMTP settings."""
+
+
+class EmailSendError(Exception):
+    pass
+
+
+def _severity_value(value: str) -> int:
+    return SEVERITY_ORDER.get(value, 0)
+
+
+def _should_notify_severity(severity: str, *, config: EmailConfig) -> bool:
+    return _severity_value(severity) >= _severity_value(config.min_severity)
+
+
+def parse_mail_recipients(mail_to: str) -> list[str]:
+    return [part.strip() for part in re.split(r"[,;]", mail_to) if part.strip()]
+
+
+def send_email_message(
+    subject: str,
+    body: str,
+    *,
+    config: EmailConfig | None = None,
+    force: bool = False,
+) -> None:
+    cfg = config or get_effective_email_config()
+    if not force and not cfg.active:
+        return
+    if not cfg.configured:
+        if force:
+            raise EmailNotConfiguredError("SMTP: не задан host, from или to")
+        return
+
+    recipients = parse_mail_recipients(cfg.mail_to)
+    if not recipients:
+        if force:
+            raise EmailNotConfiguredError("SMTP: список получателей пуст")
+        return
+
+    msg = MIMEText(body, "plain", "utf-8")
+    msg["Subject"] = subject
+    msg["From"] = cfg.mail_from
+    msg["To"] = ", ".join(recipients)
+
+    try:
+        if cfg.smtp_ssl:
+            server: smtplib.SMTP = smtplib.SMTP_SSL(cfg.smtp_host, cfg.smtp_port, timeout=12)
+        else:
+            server = smtplib.SMTP(cfg.smtp_host, cfg.smtp_port, timeout=12)
+        with server:
+            server.ehlo()
+            if cfg.smtp_starttls and not cfg.smtp_ssl:
+                server.starttls()
+                server.ehlo()
+            if cfg.smtp_user:
+                server.login(cfg.smtp_user, cfg.smtp_password)
+            server.sendmail(cfg.mail_from, recipients, msg.as_string())
+    except Exception as exc:
+        logger.exception("smtp send failed")
+        raise EmailSendError(str(exc)) from exc
+
+
+def send_email_test_message(*, config: EmailConfig | None = None) -> None:
+    cfg = config or get_effective_email_config()
+    if not cfg.enabled:
+        raise EmailNotConfiguredError("Email отключён (enabled=false)")
+    if not cfg.configured:
+        raise EmailNotConfiguredError("Не задан SMTP host, from или to")
+    send_email_message(
+        "SAC: тестовое письмо",
+        "Тестовое сообщение Security Alert Center.\nКанал SMTP для оповещений работает.",
+        config=cfg,
+        force=True,
+    )
+
+
+def notify_event(event: Event, *, db: Session | None = None) -> None:
+    cfg = get_effective_email_config(db)
+    if not cfg.active or not _should_notify_severity(event.severity, config=cfg):
+        return
+    host = event.host.hostname if event.host else "unknown"
+    body = (
+        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}"
+    )
+    try:
+        send_email_message(f"SAC: {event.type} ({event.severity})", body, config=cfg)
+    except EmailSendError:
+        logger.exception("notify_event email failed event_id=%s", event.event_id)
+
+
+def notify_problem(problem: Problem, event: Event | None = None, *, db: Session | None = None) -> None:
+    cfg = get_effective_email_config(db)
+    if not cfg.active or not _should_notify_severity(problem.severity, config=cfg):
+        return
+    host = problem.host.hostname if problem.host else "unknown"
+    related = ""
+    if event is not None:
+        related = f"\nEvent: {event.type} ({event.severity})"
+    body = (
+        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}"
+    )
+    try:
+        send_email_message(f"SAC Problem: {problem.title}", body, config=cfg)
+    except EmailSendError:
+        logger.exception("notify_problem email failed problem_id=%s", problem.id)