feat(api): add stats chart endpoint for admin access with time series data

feat(dayjs): integrate dayjs for date handling and formatting across the application
refactor(routes): update date handling in id-tags, transactions, users, and dashboard routes to use dayjs
style(globals): improve CSS variable definitions for better readability and consistency
deps: add dayjs as a dependency for date manipulation

apps/web/lib/dayjs.ts

@@ -0,0 +1,8 @@
+import dayjs from "dayjs";
+import relativeTime from "dayjs/plugin/relativeTime";
+import "dayjs/locale/zh-cn";
+
+dayjs.extend(relativeTime);
+dayjs.locale("zh-cn");
+
+export default dayjs;