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

miniprogram/pages/profile/profile.js

@@ -31,7 +31,32 @@ Page({
   },
 
   onManageDevice: function () {
-    wx.navigateTo({ url: '/pages/scan/scan' })
+    var self = this
+    if (this.data.deviceCount > 0) {
+      wx.showActionSheet({
+        itemList: ['解绑当前设备'],
+        success: function (res) {
+          if (res.tapIndex === 0) {
+            wx.showModal({
+              title: '确认解绑',
+              content: '解绑后将无法使用该设备，确定要解绑吗？',
+              success: function (modalRes) {
+                if (modalRes.confirm) {
+                  http.post('/api/v1/device/unbind', {}).then(function () {
+                    wx.showToast({ title: '已解绑', icon: 'success' })
+                    self.loadProfile()
+                  }).catch(function (err) {
+                    wx.showToast({ title: err.message || '解绑失败', icon: 'none' })
+                  })
+                }
+              }
+            })
+          }
+        }
+      })
+    } else {
+      wx.navigateTo({ url: '/pages/scan/scan' })
+    }
   },
 
   onViewSubscription: function () {

miniprogram/pages/profile/profile.wxml

@@ -20,6 +20,8 @@
       <view class="menu-item" bindtap="onManageDevice">
         <view class="menu-icon">📱</view>
         <view class="menu-text">我的设备</view>
+        <text class="menu-device-status" wx:if="{{deviceCount > 0}}">已绑定</text>
+        <text class="menu-device-status menu-device-unbound" wx:else>未绑定</text>
         <text class="menu-arrow">›</text>
       </view>
       <view class="menu-item" bindtap="onViewHistory">

miniprogram/pages/profile/profile.wxss

@@ -98,6 +98,15 @@
   font-size: 32rpx;
 }
 
+.menu-device-status {
+  font-size: 24rpx;
+  color: #52c41a;
+  margin-right: 8rpx;
+}
+.menu-device-unbound {
+  color: #999;
+}
+
 .logout-btn {
   text-align: center;
   color: #ff4d4f;