fix: resolve 8 bugs and add admin features

Miniprogram:
- Profile "我的设备": show unbind option when device bound, scan when not
- Add device status indicator (已绑定/未绑定) to profile menu

Admin console:
- Login: add @confirm to inputs so Enter key submits the form
- Record detail: wire up 详情 link with modal showing full record info
- Dashboard: add subscription stats row (月卡/年卡/试用/收入)
- Subscription: add 取消 action for active subscriptions
- Format: fix -8h timezone display for UTC ISO date strings

Server:
- POST /api/v1/admin/subscriptions/cancel: cancel active subscriptions
- Dashboard API: include sub_stats (plan counts + monthly revenue)
- IP extraction: add X-Forwarded-For fallback for logging

server/src/lib/request.js

@@ -38,7 +38,7 @@ function createContext(event) {
     query: parseQuery(event),
     body: parseBody(event),
     params: {},
-    ip: event.requestContext && event.requestContext.sourceIp || ''
+    ip: event.requestContext && event.requestContext.sourceIp || (event.headers && (event.headers['x-forwarded-for'] || event.headers['X-Forwarded-For'] || '').split(',')[0].trim()) || ''
   }
 }