refactoring for recipient addition page

frontend/pweb/lib/utils/recipient/filtering.dart

@@ -0,0 +1,28 @@
+import 'package:pshared/models/recipient/filter.dart';
+import 'package:pshared/models/recipient/recipient.dart';
+import 'package:pshared/models/recipient/status.dart';
+
+
+List<Recipient> filterRecipients({
+  required List<Recipient> recipients,
+  RecipientFilter filter = RecipientFilter.all,
+  String query = '',
+}) {
+  var filtered = recipients.where((r) {
+    switch (filter) {
+      case RecipientFilter.ready:
+        return r.status == RecipientStatus.ready;
+      case RecipientFilter.registered:
+        return r.status == RecipientStatus.registered;
+      case RecipientFilter.notRegistered:
+        return r.status == RecipientStatus.notRegistered;
+      case RecipientFilter.all:
+        return true;
+    }
+  }).toList();
+
+  final normalizedQuery = query.trim().toLowerCase();
+  if (normalizedQuery.isEmpty) return filtered;
+
+  return filtered.where((r) => r.matchesQuery(normalizedQuery)).toList();
+}