fix: use setUTCDate in getNextRecheckDate to avoid local-timezone off-by-one

lib/notifications/effectiveness-recheck.ts

@@ -14,7 +14,7 @@ export function getNextRecheckDate(verifiedAt: string, currentRound: number): st
   const days = NEXT_INTERVAL_DAYS[currentRound]
   if (days === null || days === undefined) return null
   const base = new Date(verifiedAt)
-  base.setDate(base.getDate() + days)
+  base.setUTCDate(base.getUTCDate() + days)
   return base.toISOString().split('T')[0]
 }