feat: 대시보드에 인증일 컬럼 추가

- 테이블 헤더에 '인증' 컬럼 추가
- 카카오 인증자: 노란 뱃지 + 인증일 (updated_at)
- 미인증: 회색 '미인증' 뱃지

backend/app.py

@@ -1840,7 +1840,7 @@ def admin():
 
     # 최근 가입 사용자 (20명)
     cursor.execute("""
-        SELECT id, nickname, phone, mileage_balance, created_at
+        SELECT id, nickname, phone, mileage_balance, created_at, updated_at
         FROM users
         ORDER BY created_at DESC
         LIMIT 20
@@ -1852,6 +1852,7 @@ def admin():
     for user in recent_users_raw:
         user_dict = dict(user)
         user_dict['created_at'] = utc_to_kst_str(user['created_at'])
+        user_dict['updated_at'] = utc_to_kst_str(user['updated_at']) if user['updated_at'] else None
         recent_users.append(user_dict)
 
     # 최근 적립 내역 (50건)

backend/templates/admin.html

@@ -472,23 +472,24 @@
                             <th>전화번호</th>
                             <th>포인트</th>
                             <th>가입일</th>
+                            <th>인증</th>
                         </tr>
                     </thead>
                     <tbody>
                         {% for user in recent_users %}
                         <tr style="cursor: pointer;" onclick="showUserDetail({{ user.id }})">
                             <td>{{ user.id }}</td>
-                            <td style="color: #6366f1; font-weight: 600;">
-                                {{ user.nickname }}
-                                {% if user.nickname != '고객' %}
-                                <span style="display: inline-flex; align-items: center; gap: 2px; background: #FEE500; color: #3C1E1E; font-size: 10px; font-weight: 700; padding: 2px 6px; border-radius: 8px; margin-left: 4px;">💬</span>
-                                {% else %}
-                                <span style="display: inline-flex; align-items: center; background: #e9ecef; color: #868e96; font-size: 10px; font-weight: 600; padding: 2px 6px; border-radius: 8px; margin-left: 4px;">미인증</span>
-                                {% endif %}
-                            </td>
+                            <td style="color: #6366f1; font-weight: 600;">{{ user.nickname }}</td>
                             <td class="phone-masked">{{ user.phone[:3] }}-{{ user.phone[3:7] }}-{{ user.phone[7:] if user.phone|length > 7 else '' }}</td>
                             <td class="points-positive">{{ "{:,}".format(user.mileage_balance) }}P</td>
                             <td>{{ user.created_at[:16].replace('T', ' ') }}</td>
+                            <td>
+                                {% if user.nickname != '고객' %}
+                                <span style="display: inline-flex; align-items: center; gap: 3px; background: #FEE500; color: #3C1E1E; font-size: 10px; font-weight: 700; padding: 3px 8px; border-radius: 10px;">💬 {{ user.updated_at[:10] if user.updated_at else '-' }}</span>
+                                {% else %}
+                                <span style="display: inline-flex; align-items: center; background: #f1f3f5; color: #868e96; font-size: 10px; font-weight: 600; padding: 3px 8px; border-radius: 10px;">미인증</span>
+                                {% endif %}
+                            </td>
                         </tr>
                         {% endfor %}
                     </tbody>