feat: add Overseerr migration

server/lib/settings/migrations/0000_overseerr_merge.ts

@@ -0,0 +1,15 @@
+import { MediaServerType } from '@server/constants/server';
+import type { AllSettings } from '@server/lib/settings';
+
+const overseerrMerge = (settings: any): AllSettings => {
+  if (settings.main.mediaServerType) {
+    return settings; // already migrated
+  }
+  const newSettings = { ...settings };
+  newSettings.main.mediaServerType = MediaServerType.PLEX;
+  newSettings.main.applicationTitle = 'Seerr';
+  newSettings.notifications.agents.email.options.senderName = 'Seerr';
+  return newSettings;
+};
+
+export default overseerrMerge;