Implement cross-platform push completion handling for background tasks (opt-in).

Added Display.notifyPushCompletion() to manually signal the completion of a background push task.
This mechanism is OPT-IN via the `delayPushCompletion` (or `android.delayPushCompletion`/`ios.delayPushCompletion`) build hint.

If the hint is present and true:
- Android: Acquires a `PARTIAL_WAKE_LOCK` upon receiving a push, preventing the device from sleeping until `notifyPushCompletion()` is called (or timeout).
- iOS: Ensures the `remote-notification` background mode is enabled and delays firing the system completion handler until `notifyPushCompletion()` is called.

If the hint is NOT present (default behavior):
- Android: No wake lock is acquired.
- iOS: The completion handler is fired immediately after the push callback.

Updated `IOSImplementation`, `AndroidImplementation`, `PushNotificationService`, `AndroidGradleBuilder`, and `IPhoneBuilder`.

Author: google-labs-jules[bot]

Ports/Android/src/com/codename1/impl/android/PushNotificationService.java

@@ -109,14 +109,17 @@ public void onDestroy() {
     public void push(final String value) {
         final PushCallback callback = getPushCallbackInstance();
         if(callback != null) {
-            AndroidImplementation.acquirePushWakeLock(30000);
+            final boolean delayPushCompletion = "true".equals(Display.getInstance().getProperty("delayPushCompletion", "false")) ||
+                    "true".equals(Display.getInstance().getProperty("android.delayPushCompletion", "false"));
+            if (delayPushCompletion) {
+                AndroidImplementation.acquirePushWakeLock(30000);
+            }
             Display.getInstance().callSerially(new Runnable() {
                 public void run() {
                     try {
                         callback.push(value);
                     } finally {
-                        if (!"true".equals(Display.getInstance().getProperty("delayPushCompletion", "false")) &&
-                            !"true".equals(Display.getInstance().getProperty("android.delayPushCompletion", "false"))) {
+                        if (!delayPushCompletion) {
                             Display.getInstance().notifyPushCompletion();
                         }
                     }

maven/codenameone-maven-plugin/src/main/java/com/codename1/builders/AndroidGradleBuilder.java

@@ -1163,6 +1163,10 @@ public boolean build(File sourceZip, final BuildRequest request) throws BuildExc
         playFlag = "true";
 
         gpsPermission = request.getArg("android.gpsPermission", "false").equals("true");
+        if (request.getArg("android.delayPushCompletion", "false").equals("true") ||
+                request.getArg("delayPushCompletion", "false").equals("true")) {
+            wakeLock = true;
+        }
         mediaPlaybackPermission = false;
         try {
             scanClassesForPermissions(dummyClassesDir, new Executor.ClassScanner() {

maven/codenameone-maven-plugin/src/main/java/com/codename1/builders/IPhoneBuilder.java

@@ -2380,7 +2380,8 @@ public boolean accept(File file, String string) {
             }
         }
         String backgroundModesStr = request.getArg("ios.background_modes", null);
-        if (includePush) {
+        if (includePush || "true".equals(request.getArg("ios.delayPushCompletion", "false")) ||
+                "true".equals(request.getArg("delayPushCompletion", "false"))) {
             if (backgroundModesStr == null || !backgroundModesStr.contains("remote-notification")) {
                 if (backgroundModesStr == null) {
                     backgroundModesStr = "";