refactor: 确立独立子工程架构 (backend, admin, mpuniapp) 并同步更新 AGENTS.md 规范

admin/src/settings.json

@@ -0,0 +1,8 @@
+{
+  "colorWeek": false,
+  "navbar": true,
+  "menu": true,
+  "footer": true,
+  "themeColor": "#165DFF",
+  "menuWidth": 220
+}