feat(admin): 관리자 대시보드 + 회원 상세 화면

- 대시보드(/admin/dashboard, 기본 랜딩): 요약 카드(총회원·금일 신규/탈퇴·DAU/WAU/MAU),
  접속자 추이(일/주/월 토글), 티어별 회원수, 시군구 지역 분포 — 모두 체크인 기반
- 회원 상세(/admin/members/:id): 프로필 + 강아지/체크인/매칭/구독 이력, 목록에서 상세 버튼
- adminStats API 모듈, 좌측 메뉴에 대시보드 추가

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/router/index.ts

@@ -29,12 +29,22 @@ const routes: RouteRecordRaw[] = [
     component: () => import('@/layouts/AdminLayout.vue'),
     meta: { requiresAdmin: true },
     children: [
-      { path: '', redirect: { name: 'admin-members' } },
+      { path: '', redirect: { name: 'admin-dashboard' } },
+      {
+        path: 'dashboard',
+        name: 'admin-dashboard',
+        component: () => import('@/pages/admin/AdminDashboardPage.vue'),
+      },
       {
         path: 'members',
         name: 'admin-members',
         component: () => import('@/pages/admin/AdminMembersPage.vue'),
       },
+      {
+        path: 'members/:id',
+        name: 'admin-member-detail',
+        component: () => import('@/pages/admin/AdminMemberDetailPage.vue'),
+      },
     ],
   },
 ]
@@ -72,7 +82,7 @@ router.beforeEach(async (to) => {
     return { name: 'admin-login' }
   }
   if (to.name === 'admin-login' && admin.isAdmin) {
-    return { name: 'admin-members' }
+    return { name: 'admin-dashboard' }
   }
   return true
 })