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

server/src/lib/serverless.js

@@ -0,0 +1,63 @@
+const http = require('http')
+
+module.exports = function serverless(app) {
+  return async function handler(event) {
+    const method = String(event.httpMethod || event.method || 'GET').toUpperCase()
+    const path = event.path || '/'
+    const headers = event.headers || {}
+    const qs = event.queryStringParameters || {}
+    const qsStr = Object.keys(qs).map(k => encodeURIComponent(k) + '=' + encodeURIComponent(qs[k])).join('&')
+    const url = path + (qsStr ? '?' + qsStr : '')
+
+    let rawBody = event.body || ''
+    if (event.isBase64Encoded && rawBody) rawBody = Buffer.from(rawBody, 'base64').toString('utf8')
+
+    return new Promise((resolve) => {
+      const req = new http.IncomingMessage()
+      req.method = method
+      req.url = url
+      req.headers = {}
+      Object.keys(headers).forEach(k => { req.headers[k.toLowerCase()] = headers[k] })
+      if (event.requestContext && event.requestContext.sourceIp) {
+        req.headers['x-forwarded-for'] = req.headers['x-forwarded-for'] || event.requestContext.sourceIp
+      }
+
+      const res = new http.ServerResponse(req)
+      let body = ''
+      const resHeaders = {}
+
+      res.writeHead = function (statusCode, reasonOrHeaders, maybeHeaders) {
+        res.statusCode = statusCode
+        const h = maybeHeaders || (typeof reasonOrHeaders === 'object' ? reasonOrHeaders : {})
+        Object.assign(resHeaders, h)
+      }
+
+      const originalSetHeader = res.setHeader.bind(res)
+      res.setHeader = function (name, value) {
+        resHeaders[name.toLowerCase()] = value
+        originalSetHeader(name, value)
+      }
+
+      res.end = function (chunk) {
+        if (chunk) body += chunk
+        resolve({
+          isBase64Encoded: false,
+          statusCode: res.statusCode || 200,
+          headers: Object.assign({
+            'content-type': 'application/json; charset=utf-8'
+          }, resHeaders),
+          body
+        })
+      }
+
+      res.write = function (chunk) { body += chunk }
+
+      if (rawBody) {
+        req.push(rawBody)
+      }
+      req.push(null)
+
+      app(req, res)
+    })
+  }
+}