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

admin-console/src/utils/useList.js

@@ -0,0 +1,81 @@
+import { get } from './request'
+
+/**
+ * Creates a mixin for paginated list pages.
+ *
+ * Eliminates the repeated data/computed/methods boilerplate for:
+ *   - records[], total, page, pageSize, totalPages
+ *   - loadList(), onPage(), onSearch()
+ *
+ * Usage:
+ *   import { listMixin } from '../../utils/useList'
+ *
+ *   export default {
+ *     mixins: [listMixin('/api/v1/admin/devices')],
+ *     methods: {
+ *       reload() {
+ *         this.loadList({ keyword: this.keyword })
+ *       }
+ *     }
+ *   }
+ *
+ * @param {string} apiPath - API endpoint path (passed to get())
+ * @param {object} opts
+ * @param {number} [opts.pageSize=20] - Items per page
+ */
+export function listMixin(apiPath, opts = {}) {
+  return {
+    data() {
+      return {
+        records: [],
+        total: 0,
+        page: 1,
+        pageSize: opts.pageSize || 20
+      }
+    },
+    computed: {
+      totalPages() {
+        return Math.ceil(this.total / this.pageSize) || 1
+      }
+    },
+    methods: {
+      async loadList(extraParams = {}) {
+        try {
+          var params = { page: this.page, page_size: this.pageSize }
+          // Merge extra params, dropping falsy values to keep request clean
+          var keys = Object.keys(extraParams)
+          for (var i = 0; i < keys.length; i++) {
+            var k = keys[i]
+            if (extraParams[k] !== '' && extraParams[k] != null) {
+              params[k] = extraParams[k]
+            }
+          }
+          var data = await get(apiPath, params)
+          this.records = data.records || []
+          this.total = data.total || 0
+          this.onListLoaded(data)
+        } catch (e) {
+          uni.showToast({ title: '加载失败', icon: 'none' })
+        }
+      },
+      /**
+       * Override in page to handle extra response data (e.g. stats).
+       */
+      onListLoaded(_data) {},
+      onPage(p) {
+        this.page = p
+        this.reload()
+      },
+      onSearch() {
+        this.page = 1
+        this.reload()
+      },
+      /**
+       * Override in page to call loadList() with current filters.
+       */
+      reload() {
+        this.loadList()
+      }
+    }
+  }
+}