feat: delete host from UI with events and problems cleanup

DELETE /api/v1/hosts/{id} (JWT); host reappears on next agent ingest

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

backend/app/services/host_delete.py

@@ -0,0 +1,51 @@
+"""Удаление хоста и связанных events/problems (ручная очистка UI)."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from sqlalchemy import delete, or_, select
+from sqlalchemy.orm import Session
+
+from app.models import Event, Host, Problem, ProblemEvent
+
+
+@dataclass(frozen=True)
+class HostDeleteResult:
+    host_id: int
+    hostname: str
+    deleted_events: int
+    deleted_problems: int
+
+
+def delete_host_and_related(db: Session, host_id: int) -> HostDeleteResult | None:
+    host = db.get(Host, host_id)
+    if host is None:
+        return None
+
+    hostname = host.hostname
+    event_ids = list(db.scalars(select(Event.id).where(Event.host_id == host_id)).all())
+    problem_ids = list(db.scalars(select(Problem.id).where(Problem.host_id == host_id)).all())
+
+    if event_ids or problem_ids:
+        link_filter = []
+        if event_ids:
+            link_filter.append(ProblemEvent.event_id.in_(event_ids))
+        if problem_ids:
+            link_filter.append(ProblemEvent.problem_id.in_(problem_ids))
+        db.execute(delete(ProblemEvent).where(or_(*link_filter)))
+
+    if problem_ids:
+        db.execute(delete(Problem).where(Problem.id.in_(problem_ids)))
+    if event_ids:
+        db.execute(delete(Event).where(Event.id.in_(event_ids)))
+
+    db.delete(host)
+    db.flush()
+
+    return HostDeleteResult(
+        host_id=host_id,
+        hostname=hostname,
+        deleted_events=len(event_ids),
+        deleted_problems=len(problem_ids),
+    )