feat: webhook notification channel with UI and ingest dispatch

Add webhook config (DB/env), JSON POST on events/problems, settings API,
Settings UI section, and notify_dispatch for multi-channel ingest.

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

backend/app/services/notify_dispatch.py

@@ -0,0 +1,16 @@
+"""Dispatch ingest notifications to all configured channels."""
+
+from sqlalchemy.orm import Session
+
+from app.models import Event, Problem
+from app.services import telegram_notify, webhook_notify
+
+
+def notify_event(event: Event, *, db: Session | None = None) -> None:
+    telegram_notify.notify_event(event, db=db)
+    webhook_notify.notify_event(event, db=db)
+
+
+def notify_problem(problem: Problem, event: Event | None = None, *, db: Session | None = None) -> None:
+    telegram_notify.notify_problem(problem, event, db=db)
+    webhook_notify.notify_problem(problem, event, db=db)