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/app/dashboard/charge-points/page.tsx

@@ -27,6 +27,7 @@ import Link from "next/link";
 import { ScrollFade } from "@/components/scroll-fade";
 import { api, type ChargePoint } from "@/lib/api";
 import { useSession } from "@/lib/auth-client";
+import dayjs from "@/lib/dayjs";
 
 const statusLabelMap: Record<string, string> = {
   Available: "空闲中",
@@ -473,7 +474,7 @@ export default function ChargePointsPage() {
                   </Table.Cell>
                   <Table.Cell>
                     {cp.lastHeartbeatAt ? (
-                      new Date(cp.lastHeartbeatAt).toLocaleString("zh-CN")
+                      dayjs(cp.lastHeartbeatAt).format("YYYY/M/D HH:mm:ss")
                     ) : (
                       <span className="text-muted">—</span>
                     )}