feat: harden analytics dashboard

lib/query-date-range.ts

@@ -0,0 +1,13 @@
+import { query } from "./db";
+
+// ── 数据时间边界 ────────────────────────────────────────────────
+
+export async function getDateRange(): Promise<{ minDate: string; maxDate: string }> {
+  const rows = await query(
+    `SELECT
+       ((MIN(to_timestamp(created_at)) AT TIME ZONE 'Asia/Shanghai')::date)::text as min_date,
+       ((MAX(to_timestamp(created_at)) AT TIME ZONE 'Asia/Shanghai')::date)::text as max_date
+     FROM logs WHERE type = 2`
+  );
+  return { minDate: rows[0]?.min_date ?? "", maxDate: rows[0]?.max_date ?? "" };
+}