enhance leaderboard reporting and grouping

frontend-web/src/core/admin/api.ts

@@ -133,6 +133,11 @@ export interface AdminUserAnalyticsResponse {
   trends: AdminLeaderboardTrendPoint[];
 }
 
+export interface AdminLeaderboardReportResponse {
+  report: string;
+  generated_at: string;
+}
+
 const base = () => `${getBackendBaseURL()}/api/admin/users`;
 
 async function parse<T>(res: Response, what: string): Promise<T> {
@@ -208,6 +213,24 @@ export async function getUserAnalytics(
   );
 }
 
+export async function generateUserLeaderboardReport(
+  range: { since: string; until: string; days?: number },
+  limit = 30,
+): Promise<AdminLeaderboardReportResponse> {
+  const params = new URLSearchParams({
+    days: String(range.days ?? 30),
+    since: range.since,
+    until: range.until,
+    limit: String(limit),
+  });
+  return parse(
+    await apiFetch(`${base()}/leaderboard/report?${params}`, {
+      method: "POST",
+    }),
+    "Failed to generate leaderboard report",
+  );
+}
+
 export async function addAdminMemoryEntry(
   userId: string,
   content: string,