feat: guard closed core recruitment page

Author: CSE-Shaco

src/app/recruit/core/completed/page.tsx

@@ -1,6 +1,7 @@
 'use client'
 
 import Link from 'next/link'
+import { useSearchParams } from 'next/navigation'
 import { GdgLogo, GdgButton } from '@/components/ui/design-system'
 
 function Bullet({ children }: { children: React.ReactNode }) {
@@ -15,17 +16,28 @@ function Bullet({ children }: { children: React.ReactNode }) {
 }
 
 export default function RecruitCoreCompleted() {
+  const searchParams = useSearchParams()
+  const isClosed = searchParams.get('status') === 'closed'
+
   return (
     <main className="min-h-screen bg-black overflow-x-hidden">
       <div className="relative z-10 pt-18 pb-32 mobile:pt-12 mobile:pb-24 layout-grid layout-grid--narrow-screen layout-grid--4 gap-y-10">
         {/* Header */}
         <div className="col-span-4 flex items-center gap-3 mobile:gap-2">
           <GdgLogo mode="auto" />
-          <h1 className="typo-pc-h3 text-white mobile:typo-m-h2">Core Member 지원 완료</h1>
+          <h1 className="typo-pc-h3 text-white mobile:typo-m-h2">
+            {isClosed ? 'Core Member 지원 마감' : 'Core Member 지원 완료'}
+          </h1>
         </div>
 
         {/* Content Sections - Step 2 UI 이관 */}
         <div className="col-span-4 flex flex-col gap-10 w-full">
+          <div className="rounded-xl bg-gray-100 px-4 py-3 text-white typo-pc-b2 mobile:typo-m-b3">
+            {isClosed
+              ? '코어 지원 기간이 종료되어 더 이상 지원서를 제출할 수 없습니다.'
+              : '지원이 정상적으로 완료되었습니다. 이후 일정은 아래 안내를 확인해 주세요.'}
+          </div>
+
           <div className="space-y-2">
             <p className="pl-2 typo-pc-s2 mobile:typo-m-s1 text-white">모집 일정</p>
             <div className="rounded-xl bg-gray-100 px-4 py-3 text-white">

src/app/recruit/core/page.tsx

@@ -61,6 +61,7 @@ const TEAM_OPTIONS = [
   { id: 'TECH', label: 'TECH' },
   { id: 'PR_DESIGN', label: 'PR·DESIGN' }
 ] as const
+const CORE_RECRUIT_DEADLINE = '2026-03-14T23:59:59+09:00'
 
 const unwrapPrefill = (raw: unknown): PrefillPayload | null => {
   if (!raw || typeof raw !== 'object') return null
@@ -202,6 +203,7 @@ export default function RecruitCore() {
   const [isSubmitting, setIsSubmitting] = useState(false)
   const [scheduleChecked, setScheduleChecked] = useState(false)
   const [agreementChecked, setAgreementChecked] = useState(false)
+  const isRecruitClosed = Date.now() > new Date(CORE_RECRUIT_DEADLINE).getTime()
 
   const [formData, setFormData] = useState<RecruitFormData>({
     name: '',
@@ -242,6 +244,19 @@ export default function RecruitCore() {
   }, [currentStep, formData, scheduleChecked, agreementChecked])
 
   useEffect(() => {
+    if (!isRecruitClosed) {
+      return
+    }
+
+    alert('코어 지원 기간이 종료되었습니다.')
+    router.replace('/recruit/core/completed?status=closed')
+  }, [isRecruitClosed, router])
+
+  useEffect(() => {
+    if (isRecruitClosed) {
+      return
+    }
+
     let active = true
 
     const fetchPrefill = async () => {
@@ -278,7 +293,7 @@ export default function RecruitCore() {
     return () => {
       active = false
     }
-  }, [apiClient, router])
+  }, [apiClient, isRecruitClosed, router])
 
   const validateStep = (step: RecruitStep) => {
     const nextErrors: Record<string, boolean> = {}
@@ -399,6 +414,12 @@ export default function RecruitCore() {
   const handleSubmit = async (event: FormEvent<HTMLFormElement>) => {
     event.preventDefault()
 
+    if (isRecruitClosed) {
+      alert('코어 지원 기간이 종료되었습니다.')
+      router.replace('/recruit/core/completed?status=closed')
+      return
+    }
+
     if (!validateStep(currentStep)) return
 
     if (currentStep < 3) {