🎉 Create the iOS extension widget target

ios/Runner/Services/GroupDefaultSync.swift

@@ -0,0 +1,35 @@
+//
+//  GroupDefaultSync.swift
+//  Runner
+//
+//  Created by LittleSheep on 2026/1/3.
+//
+
+import Foundation
+
+private let flutterKeyPrefix = "flutter."
+
+private let flutterKeysToSync: [String] = [
+    "dyn_user_tk"
+]
+
+func syncDefaultsToGroup() {
+    let standard = UserDefaults.standard
+    let shared = UserDefaults(suiteName: "dev.solsynth.solian")
+
+    guard let shared else {
+        print("[iOS] App Group UserDefaults not available")
+        return
+    }
+
+    for key in flutterKeysToSync {
+        guard key.hasPrefix(flutterKeyPrefix) else { continue }
+
+        if let value = standard.object(forKey: key) {
+            print("[iOS] Syncing key to App Group: \(key)")
+            shared.set(value, forKey: key)
+        }
+    }
+
+    shared.synchronize()
+}