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/ble-connect/ble-connect.js

@@ -96,16 +96,13 @@ Page({
     this.startBleConnect()
   },
 
-  _mockConfirmBind: function () {
+  onMockConnect: function () {
     var self = this
+    clearTimeout(this._scanTimer)
+    ble.stopScan()
     self.setData({ state: 'binding' })
-    http.post('/api/v1/device/bind', {
+    http.post('/api/v1/device/mock-bind', {
       device_id: self.data.deviceId
-    }).then(function (data) {
-      return http.post('/api/v1/device/bind/confirm', {
-        device_id: data.device_id,
-        bind_token: data.bind_token
-      })
     }).then(function () {
       self.setData({ state: 'done' })
       wx.redirectTo({
@@ -116,15 +113,7 @@ Page({
     })
   },
 
-  onMockConnect: function () {
-    clearTimeout(this._scanTimer)
-    ble.stopScan()
-    this._mockConfirmBind()
-  },
-
   onMockBindSuccess: function () {
-    clearTimeout(this._scanTimer)
-    ble.stopScan()
-    this._mockConfirmBind()
+    this.onMockConnect()
   }
 })