🛡️ Sentinel: [CRITICAL] Fix Missing authentication on admin endpoints

[seonghobae]

🚨 Severity: CRITICAL
💡 Vulnerability: AdminController의 모든 관리자 전용 API(조회, 삭제, 재시도)에 인증/인가 과정이 누락되어, 권한 없는 사용자가 관리자 기능에 임의로 접근할 수 있는 문제가 발생했습니다.
🎯 Impact: 인가되지 않은 외부 사용자가 중요 데이터(변환 작업)를 무단으로 열람, 삭제, 재시도하여 시스템 상태를 조작하거나 자원을 고갈시킬 수 있는 심각한 위험이 있었습니다.
🔧 Fix: TenantAccessService를 AdminController에 주입하고, TenantPermissions.ADMIN_READ 및 ADMIN_WRITE 상수를 추가하여 엔드포인트 진입 시 적절한 권한을 요구하도록 수정했습니다.
✅ Verification: AdminControllerTest를 업데이트하여 Mock 객체를 통해 권한 요구 로직을 검증했으며, 테스트를 통과하고 100% 커버리지를 달성했습니다.

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PR created automatically by Jules for task 12756902097463012709 started by @seonghobae

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