perf(admin): optimize large-dataset loading for dashboard/users/accounts/ops

backend/internal/handler/admin/id_list_utils.go

@@ -0,0 +1,25 @@
+package admin
+
+import "sort"
+
+func normalizeInt64IDList(ids []int64) []int64 {
+	if len(ids) == 0 {
+		return nil
+	}
+
+	out := make([]int64, 0, len(ids))
+	seen := make(map[int64]struct{}, len(ids))
+	for _, id := range ids {
+		if id <= 0 {
+			continue
+		}
+		if _, ok := seen[id]; ok {
+			continue
+		}
+		seen[id] = struct{}{}
+		out = append(out, id)
+	}
+
+	sort.Slice(out, func(i, j int) bool { return out[i] < out[j] })
+	return out
+}