feat(listings): 실매물 tier/금액 순수 헬퍼 + 테스트

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UHXzpsZQxKG9hQmNRfZjRS

src/pages/listings/listingsUtils.js

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+/* 실매물 판정 tier / 금액 포맷 순수 헬퍼 */
+const C = { green: '#34d399', yellow: '#f59e0b', red: '#f87171', gray: '#94a3b8' };
+
+export const SAFETY_TIER_META = Object.freeze({
+  '안전': { emoji: '🟢', color: C.green },
+  '주의': { emoji: '🟡', color: C.yellow },
+  '위험': { emoji: '🔴', color: C.red },
+  '보류': { emoji: '⚪', color: C.gray },
+});
+
+export const VALUATION_TIER_META = Object.freeze({
+  '저평가': { emoji: '🟢', color: C.green },
+  '시세':   { emoji: '🟡', color: C.yellow },
+  '고가':   { emoji: '🔴', color: C.red },
+  '보류':   { emoji: '⚪', color: C.gray },
+});
+
+export const tierMeta = (kind, tier) => {
+  const map = kind === 'valuation' ? VALUATION_TIER_META : SAFETY_TIER_META;
+  if (Object.hasOwn(map, tier)) return { ...map[tier], label: tier };
+  return { emoji: '⚪', color: C.gray, label: tier ?? '' };
+};
+
+export const formatMoney = (manwon) => {
+  if (manwon == null || manwon === '') return '-';
+  const n = Number(manwon);
+  if (Number.isNaN(n)) return '-';
+  const eok = Math.floor(n / 10000);
+  const rest = n % 10000;
+  if (eok > 0 && rest > 0) return `${eok}억 ${rest.toLocaleString('ko-KR')}만`;
+  if (eok > 0) return `${eok}억`;
+  return `${n.toLocaleString('ko-KR')}만`;
+};
+
+export const formatRatio = (ratio) => {
+  if (ratio == null) return '-';
+  const n = Number(ratio);
+  if (Number.isNaN(n)) return '-';
+  return `${(n * 100).toFixed(1)}%`;
+};