feat: remove legacy alert rules, superseded by automations

Alert rules already auto-migrate into automations on boot and the old
engine stands down after. Deletes the rule/firing tables, routes, UI,
and AI tools; keeps notification channels since automations still use
them. Also fixes automations' notify step, which still called the
deleted repository.

src/ui/api/notification-channels-api.ts

@@ -0,0 +1,56 @@
+import { rbacApi } from "@/main-axios";
+
+export interface NotificationChannel {
+  id: number;
+  userId: string;
+  name: string;
+  type: "webhook" | "ntfy" | "discord";
+  config: string;
+  enabled: boolean;
+  createdAt: string;
+}
+
+export async function getNotificationChannels(): Promise<
+  NotificationChannel[]
+> {
+  const res = await rbacApi.get("/notification-channels");
+  return res.data;
+}
+
+export type NotificationChannelPayload = Partial<
+  Omit<NotificationChannel, "config">
+> & {
+  // When creating/updating the channel the UI may pass a parsed object
+  // for `config` (e.g., { url, username }) — the backend stores it as
+  // a JSON string. Accept either a string or any structured object here.
+  // Use `unknown` to allow the component-local config types to be passed
+  // without importing them into this module.
+  config: string | unknown;
+};
+
+export async function createNotificationChannel(
+  data: NotificationChannelPayload,
+): Promise<NotificationChannel> {
+  const res = await rbacApi.post("/notification-channels", data);
+  return res.data;
+}
+
+export async function updateNotificationChannel(
+  id: number,
+  data: NotificationChannelPayload,
+): Promise<NotificationChannel> {
+  const res = await rbacApi.put(`/notification-channels/${id}`, data);
+  return res.data;
+}
+
+export async function deleteNotificationChannel(id: number): Promise<void> {
+  await rbacApi.delete(`/notification-channels/${id}`);
+}
+
+export async function testNotificationChannel(id: number): Promise<void> {
+  const res = await rbacApi.post(`/notification-channels/${id}/test`);
+  const data = res.data as { success?: boolean; error?: string };
+  if (data && data.success === false) {
+    throw new Error(data.error || "Test notification failed");
+  }
+}