Add retroactiveAchievements API function

src/api/admin.ts

@@ -73,3 +73,15 @@ export async function deleteChallenge(id: string) {
   const { data } = await apiClient.delete(`/admin/daily-challenges/${id}`);
   return data;
 }
+
+export interface RetroactiveAchievementsResult {
+  totalAwarded: number;
+  usersAffected: number;
+}
+
+export async function retroactiveAchievements(): Promise<RetroactiveAchievementsResult> {
+  const { data } = await apiClient.post<RetroactiveAchievementsResult>(
+    '/admin/retroactive-achievements',
+  );
+  return data;
+}