feat(listings): Listings shell+스타일+라우트 배선 + 청약 교차링크 + 문서

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

src/pages/subscription/Subscription.jsx

@@ -1,5 +1,6 @@
 import React, { useState, useEffect, useMemo, useCallback } from 'react';
 import { apiGet, apiPost, apiPut, apiDelete } from '../../api';
+import { Link } from 'react-router-dom';
 import PullToRefresh from '../../components/PullToRefresh';
 import FAB from '../../components/FAB';
 import DistrictTierEditor from './components/DistrictTierEditor';
@@ -1598,6 +1599,11 @@ function Subscription() {
     return (
         <PullToRefresh onRefresh={handleRefresh}>
         <div className="sub">
+            <div style={{ display: 'flex', justifyContent: 'flex-end', marginBottom: 8 }}>
+                <Link to="/realestate/listings" style={{ fontSize: 12, color: '#f43f5e', textDecoration: 'none' }}>
+                    실매물 · 안전마진 →
+                </Link>
+            </div>
             {/* Header */}
             <div className="sub-header">
                 <div>