refactor: restructure entire project for human maintainability

Server:
- Add Express framework, replace custom router/request parser
- Create DAO layer (12 files) centralizing all 73 SQL queries
- Rewrite 7 route files as thin Express controllers calling DAOs
- Add SCF-to-Express adapter (lib/serverless.js)
- Add auth middleware (middleware/auth.js)
- Remove dead code from lib/auth.js

Admin console:
- Extract DataTable component (table + pagination)
- Extract ConfirmModal component (modal + form styles)
- Create listMixin for paginated list pages
- Move form styles to common.css for slot compatibility
- Refactor device + subscription pages as examples

Miniprogram:
- Split 734-line BLE monolith into 4 focused modules
  (protocol, connection, commands, barrel index)
- Create API module (utils/api.js) with named functions
- Create page utilities (utils/page.js)
- Refactor index + profile pages to use API module

miniprogram/pages/index/index.js

@@ -1,5 +1,5 @@
 var ble = require('../../services/ble')
-var http = require('../../utils/request')
+var api = require('../../utils/api')
 var config = require('../../config/env')
 var app = getApp()
 
@@ -49,7 +49,7 @@ Page({
 
     self.setData({ connected: ble.isConnected() })
 
-    http.get('/api/v1/device/list').then(function (data) {
+    api.getDevices().then(function (data) {
       var devices = data.devices || []
       self.setData({ hasDevice: devices.length > 0 })
       if (devices.length > 0) {
@@ -61,7 +61,7 @@ Page({
       }
     }).catch(function () {})
 
-    http.get('/api/v1/subscription').then(function (sub) {
+    api.getSubscription().then(function (sub) {
       self.setData({
         subscription: sub,
         subRemaining: sub.remaining_days || 0
@@ -125,7 +125,7 @@ Page({
     var self = this
     wx.showLoading({ title: '解绑中...' })
     ble.disconnect()
-    http.post('/api/v1/device/unbind', {}).then(function () {
+    api.unbindDevice().then(function () {
       wx.hideLoading()
       self.setData({
         hasDevice: false,
@@ -157,7 +157,7 @@ Page({
       success: function (res) {
         if (res.confirm && res.content) {
           var deviceId = res.content.trim()
-          http.post('/api/v1/device/mock-bind', { device_id: deviceId }).then(function () {
+          api.mockBind(deviceId).then(function () {
             wx.showToast({ title: '模拟绑定成功', icon: 'success' })
             self.checkState()
           }).catch(function (err) {

miniprogram/pages/profile/profile.js

@@ -1,4 +1,4 @@
-var http = require('../../utils/request')
+var api = require('../../utils/api')
 var app = getApp()
 
 Page({
@@ -15,14 +15,14 @@ Page({
 
   loadProfile: function () {
     var self = this
-    http.get('/api/v1/user/profile').then(function (profile) {
+    api.getProfile().then(function (profile) {
       self.setData({
         userInfo: profile,
         deviceCount: profile.device_count || 0
       })
     }).catch(function () {})
 
-    http.get('/api/v1/subscription').then(function (sub) {
+    api.getSubscription().then(function (sub) {
       self.setData({
         subscription: sub,
         subRemaining: sub.remaining_days || 0
@@ -42,7 +42,7 @@ Page({
               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 () {
+                  api.unbindDevice().then(function () {
                     wx.showToast({ title: '已解绑', icon: 'success' })
                     self.loadProfile()
                   }).catch(function (err) {