fix: compilation errors in iOS and Android after Pigeon migration

- Fix Swift compilation error in iOS BackgroundWorker by replacing non-existent mapKeys with proper Dictionary conversion
- Add missing getCallbackHandle static method to Android SharedPreferenceHelper
- Verify both iOS and Android builds compile successfully

Author: ened

workmanager_android/android/src/main/kotlin/dev/fluttercommunity/workmanager/SharedPreferenceHelper.kt

@@ -19,6 +19,11 @@ class SharedPreferenceHelper(
         private const val SHARED_PREFS_FILE_NAME = "flutter_workmanager_plugin"
         private const val CALLBACK_DISPATCHER_HANDLE_KEY =
             "dev.fluttercommunity.workmanager.CALLBACK_DISPATCHER_HANDLE_KEY"
+        
+        fun getCallbackHandle(context: Context): Long {
+            val preferences = context.getSharedPreferences(SHARED_PREFS_FILE_NAME, Context.MODE_PRIVATE)
+            return preferences.getLong(CALLBACK_DISPATCHER_HANDLE_KEY, -1L)
+        }
     }
 
     private val preferences: SharedPreferences

workmanager_apple/ios/Classes/BackgroundWorker.swift

@@ -121,7 +121,10 @@ class BackgroundWorker {
                 let taskName = self.backgroundMode.onResultSendArguments["\(WorkmanagerPlugin.identifier).DART_TASK"] ?? ""
 
                 // Convert inputData to the format expected by Pigeon
-                let pigeonInputData = self.inputData?.mapKeys { $0 as String? }.mapValues { $0 as Any? }
+                var pigeonInputData: [String?: Any?]? = nil
+                if let inputData = self.inputData {
+                    pigeonInputData = Dictionary(uniqueKeysWithValues: inputData.map { ($0.key as String?, $0.value as Any?) })
+                }
 
                 // Execute the task
                 flutterApi?.executeTask(taskName: taskName, inputData: pigeonInputData) { taskResult in