feat(admin): Phase V2-6 Admin CRM 고도화 — CRUD + 차트 + 결제 + 감사

- DB: audit_log 테이블(diff 포함) + subscriptions.admin_note + super_admin role
- Edge Functions 4개: admin-users, admin-subscriptions, admin-payments, admin-audit-log
- 공유 유틸: admin-auth.ts(권한 검증), audit.ts(감사로그 기록)
- Swagger UI: 독립 정적 페이지 + OpenAPI 3.0 spec
- CRUD 페이지: 구독 생성/수정/삭제, role 변경, 감사로그 목록/상세
- recharts: feature별 StackedBar + DAU Line + Top Users HorizontalBar
- 결제 이력: DB + Payple API 병행 조회
- 권한: super_admin만 위험 작업, admin은 조회 전용
- RLS: admin/super_admin IN 정책 + super_admin 쓰기 정책
- SQL RPC: admin_usage_by_feature, admin_top_users, admin_dau

apps/admin/src/components/admin-sidebar.tsx

@@ -9,6 +9,8 @@ import DashboardIcon from '@mui/icons-material/Dashboard'
 import PeopleIcon from '@mui/icons-material/People'
 import SubscriptionsIcon from '@mui/icons-material/Subscriptions'
 import BarChartIcon from '@mui/icons-material/BarChart'
+import HistoryIcon from '@mui/icons-material/History'
+import ApiIcon from '@mui/icons-material/Api'
 import LogoutIcon from '@mui/icons-material/Logout'
 import { PhosphorText } from '@d3ro/ui/components/ds'
 import { d3roPalette, d3roFontMono } from '@d3ro/ui/theme'
@@ -19,6 +21,11 @@ const NAV_ITEMS = [
   { key: 'users', path: '/users', label: 'Users', icon: <PeopleIcon /> },
   { key: 'subscriptions', path: '/subscriptions', label: 'Subscriptions', icon: <SubscriptionsIcon /> },
   { key: 'usage', path: '/usage', label: 'Usage', icon: <BarChartIcon /> },
+  { key: 'audit-log', path: '/audit-log', label: 'Audit Log', icon: <HistoryIcon /> },
+]
+
+const EXTERNAL_LINKS = [
+  { key: 'swagger', href: '/admin-swagger/', label: 'API Docs', icon: <ApiIcon /> },
 ]
 
 export function AdminSidebar(): React.ReactElement {
@@ -78,6 +85,41 @@ export function AdminSidebar(): React.ReactElement {
             </ListItem>
           )
         })}
+        <ListItem disablePadding sx={{ mt: 1 }}>
+          <ListItemText
+            primary="EXTERNAL"
+            primaryTypographyProps={{
+              fontFamily: d3roFontMono,
+              fontSize: 10,
+              color: d3roPalette.text.label,
+              px: 2,
+              pt: 1,
+            }}
+          />
+        </ListItem>
+        {EXTERNAL_LINKS.map((item) => (
+          <ListItem key={item.key} disablePadding>
+            <ListItemButton
+              component="a"
+              href={item.href}
+              target="_blank"
+              rel="noopener noreferrer"
+              sx={{ fontFamily: d3roFontMono }}
+            >
+              <ListItemIcon sx={{ minWidth: 36, color: d3roPalette.text.inactive }}>
+                {item.icon}
+              </ListItemIcon>
+              <ListItemText
+                primary={item.label}
+                primaryTypographyProps={{
+                  fontFamily: d3roFontMono,
+                  fontSize: 13,
+                  color: d3roPalette.text.secondary,
+                }}
+              />
+            </ListItemButton>
+          </ListItem>
+        ))}
       </List>
 
       <Box sx={{ p: 2, borderTop: `1px solid ${d3roPalette.border.default}` }}>