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/package.json

@@ -12,8 +12,8 @@
     "bcryptjs": "^2.4.3",
     "cos-nodejs-sdk-v5": "^2.14.7",
     "dotenv": "^16.4.5",
+    "express": "^5.2.1",
     "jsonwebtoken": "^9.0.2",
     "mysql2": "^3.11.3"
-  },
-  "devDependencies": {}
+  }
 }