refactor(revalidate): derive RevalidateTypes from VALID_REVALIDATE_TYPES using as const

Agent-Logs-Url: https://github.com/MobilityData/mobilitydatabase-web/sessions/abef6cf3-56bf-4193-98d6-be9048ca9b2f

Co-authored-by: Alessandro100 <18631060+Alessandro100@users.noreply.github.com>

Author: Copilot

src/app/api/revalidate/route.ts

@@ -9,22 +9,16 @@ import {
   revalidateSpecificFeeds,
 } from '../../utils/revalidate-feeds';
 
-type RevalidateTypes =
-  | 'full'
-  | 'all-feeds'
-  | 'all-gbfs-feeds'
-  | 'all-gtfs-rt-feeds'
-  | 'all-gtfs-feeds'
-  | 'specific-feeds';
-
-const VALID_REVALIDATE_TYPES: RevalidateTypes[] = [
+const VALID_REVALIDATE_TYPES = [
   'full',
   'all-feeds',
   'all-gbfs-feeds',
   'all-gtfs-rt-feeds',
   'all-gtfs-feeds',
   'specific-feeds',
-];
+] as const;
+
+type RevalidateTypes = (typeof VALID_REVALIDATE_TYPES)[number];
 
 interface RevalidateBody {
   feedIds: string[]; // only for 'specific-feeds' revalidation type