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/styles/common.css

@@ -171,3 +171,35 @@
 .input-placeholder {
   color: #bfbfbf;
 }
+
+.form-group {
+  margin-bottom: 16px;
+}
+
+.form-label {
+  display: block;
+  font-size: 14px;
+  color: #333;
+  margin-bottom: 6px;
+}
+
+.form-input {
+  width: 100%;
+  height: 36px;
+  border: 1px solid #d9d9d9;
+  border-radius: 6px;
+  padding: 0 12px;
+  font-size: 14px;
+  box-sizing: border-box;
+}
+
+.form-textarea {
+  width: 100%;
+  height: 160px;
+  border: 1px solid #d9d9d9;
+  border-radius: 6px;
+  padding: 12px;
+  font-size: 14px;
+  box-sizing: border-box;
+  resize: vertical;
+}