Clarify receive requests and add retry countdowns and device unblock controls

.env.example

@@ -31,9 +31,9 @@ MAX_URL_PAYLOAD_SIZE_KB=1024
 MAX_TEXT_PAYLOAD_SIZE_KB=256
 MAX_ITEMS_PER_TRANSFER=20
 DEFAULT_URL_RETENTION_DAYS=7
-GUEST_REQUESTS_PER_MINUTE=5
-IP_REQUESTS_PER_MINUTE=20
-PAIR_REQUESTS_PER_MINUTE=2
+GUEST_REQUESTS_PER_MINUTE=30
+IP_REQUESTS_PER_MINUTE=120
+PAIR_REQUESTS_PER_MINUTE=10
 REJECT_COOLDOWN_SECONDS=300
 # Resend 발송 설정과 실제 인증 메일 수신을 확인한 뒤 공개 가입을 엽니다.
 REGISTRATION_MODE=closed