fix: maxDuration 300→60 for Vercel hobby plan

Vercel hobby plan caps serverless functions at 60s. The heavy work
runs inside after() callbacks which have their own execution context,
so 60s is sufficient for the initial request handler.

Author: codercatdev

app/api/cron/check-research/route.ts

@@ -1,5 +1,5 @@
 export const fetchCache = 'force-no-store';
-export const maxDuration = 300;
+export const maxDuration = 60;
 
 import { type NextRequest } from 'next/server';
 import { after } from 'next/server';