Refactor admin stats API and charts data models for consistency

- Updated `AdminStatsResponse` with streamlined type annotations and added `AdminStatsData` type definition.
- Renamed chart data model fields (`totalUsers` → `total_users`, `activeUsers` → `active_users`, `members` → `value`, etc.) for alignment with backend naming conventions.
- Adjusted related test files to reflect updated data model structure.
- Improved readability of `AdminPage` component by reformatting destructuring in `useQuery`.

frontend/src/lib/api/admin.ts

@@ -2,44 +2,51 @@ import { apiClient } from './client';
 import type { Options } from './generated/sdk.gen';
 
 export interface UserGrowthData {
-    date: string;
-    total_users: number;
-    active_users: number;
+  date: string;
+  total_users: number;
+  active_users: number;
 }
 
 export interface OrgDistributionData {
-    name: string;
-    value: number;
+  name: string;
+  value: number;
 }
 
 export interface UserStatusData {
-    name: string;
-    value: number;
+  name: string;
+  value: number;
 }
 
 export interface AdminStatsResponse {
-    user_growth: UserGrowthData[];
-    organization_distribution: OrgDistributionData[];
-    user_status: UserStatusData[];
+  user_growth: UserGrowthData[];
+  organization_distribution: OrgDistributionData[];
+  user_status: UserStatusData[];
 }
 
+export type AdminStatsData = {
+  body?: never;
+  path?: never;
+  query?: never;
+  url: '/api/v1/admin/stats';
+};
+
 /**
  * Admin: Get Dashboard Stats
  *
  * Get aggregated statistics for the admin dashboard (admin only)
  */
 export const getAdminStats = <ThrowOnError extends boolean = false>(
-    options?: Options<any, ThrowOnError>
+  options?: Options<AdminStatsData, ThrowOnError>
 ) => {
-    return (options?.client ?? apiClient).get<AdminStatsResponse, any, ThrowOnError>({
-        responseType: 'json',
-        security: [
-            {
-                scheme: 'bearer',
-                type: 'http',
-            },
-        ],
-        url: '/api/v1/admin/stats',
-        ...options,
-    });
+  return (options?.client ?? apiClient).get<AdminStatsResponse, unknown, ThrowOnError>({
+    responseType: 'json',
+    security: [
+      {
+        scheme: 'bearer',
+        type: 'http',
+      },
+    ],
+    url: '/api/v1/admin/stats',
+    ...options,
+  });
 };