fix(web): type server channel event field tables explicitly

tsc -b (the production build) collapses flatMap over the as-const union of
two differently shaped readonly field tuples to unknown, failing the Docker
frontend stage; a bare tsc --noEmit accepted it. Give the field entries one
explicit shared type so flatMap and channel[field.key] resolve.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/src/pages/admin-settings/ServerNotificationChannels.tsx

@@ -41,7 +41,21 @@ import {
 } from "@/hooks/queries/admin/serverNotificationChannels";
 import { formatRelativeTime } from "@/lib/date";
 
-const EVENT_SECTIONS = [
+type ChannelNotifyKey =
+  | "notify_new_movies"
+  | "notify_new_episodes"
+  | "notify_request_submitted"
+  | "notify_request_approved"
+  | "notify_request_declined"
+  | "notify_request_fulfilled";
+
+interface ChannelNotifyField {
+  key: ChannelNotifyKey;
+  label: string;
+  defaultValue: boolean;
+}
+
+const EVENT_SECTIONS: { label: string; fields: ChannelNotifyField[] }[] = [
   {
     label: "New content",
     fields: [
@@ -58,12 +72,10 @@ const EVENT_SECTIONS = [
       { key: "notify_request_fulfilled", label: "Request fulfilled", defaultValue: false },
     ],
   },
-] as const;
+];
 
 const CHANNEL_NOTIFY_FIELDS = EVENT_SECTIONS.flatMap((section) => section.fields);
 
-type ChannelNotifyKey = (typeof EVENT_SECTIONS)[number]["fields"][number]["key"];
-
 function ChannelFormDialog({
   open,
   onOpenChange,