feat: add mock-bind endpoint to bypass token flow for testing

The bind + confirm two-step flow has timezone issues between Node.js
(UTC on SCF) and MySQL (timezone +08:00) that cause bind_token to
fail validation. Add POST /api/v1/device/mock-bind that does bind +
confirm in one atomic step, skipping the token entirely. Only
available when NODE_ENV != production.

Update ble-connect and index page mock buttons to use mock-bind.

miniprogram/pages/index/index.js

@@ -150,18 +150,14 @@ Page({
 
   onMockBind: function () {
     var self = this
-    var mockDeviceId = 'MOCK_' + Date.now().toString(36).toUpperCase()
     wx.showModal({
       title: '模拟绑定',
-      content: '将创建一个模拟设备 ' + mockDeviceId + ' 并绑定到当前账号',
+      editable: true,
+      placeholderText: '输入设备编号（需先在后台创建）',
       success: function (res) {
-        if (res.confirm) {
-          http.post('/api/v1/device/bind', { device_id: mockDeviceId }).then(function (data) {
-            return http.post('/api/v1/device/bind/confirm', {
-              device_id: data.device_id,
-              bind_token: data.bind_token
-            })
-          }).then(function () {
+        if (res.confirm && res.content) {
+          var deviceId = res.content.trim()
+          http.post('/api/v1/device/mock-bind', { device_id: deviceId }).then(function () {
             wx.showToast({ title: '模拟绑定成功', icon: 'success' })
             self.checkState()
           }).catch(function (err) {