docs: update rokt setup and migration guidance

Document explicit Rokt event subscriptions and iOS payment extension setup for shoppable ads in both README and migration notes.

Author: denischilik

MIGRATING.md

@@ -92,6 +92,6 @@ await MparticleFlutterSdk.getInstance().then((mp) => mp?.rokt.selectShoppableAds
 - **Android**: the method is exposed for API parity but is a no-op (logs a warning).
 - **Web**: not implemented — calls will throw `MissingPluginException`.
 
-Events for a shoppable ads placement are delivered on the existing `MPRoktEvents` `EventChannel` once `selectShoppableAds` has been called.
+Rokt event delivery now uses explicit subscription by identifier through `Rokt.events(...)`. Call `events(identifier, ...)` before `selectPlacements(...)` or `selectShoppableAds(...)` for that identifier.
 
-The Rokt Apple Pay payment extension (for example `RoktStripePaymentExtension`) is **not** proxied through Dart. Integrators must register it directly from native Swift/Objective-C in the host app (for example `ios/Runner/AppDelegate.swift`), after `MParticle.sharedInstance().start(with:)`. See the [Apple SDK Rokt integration section](https://github.com/mParticle/mparticle-apple-sdk/blob/main/README.md#rokt-integration) for the exact snippet.
+The Rokt payment extension (for example `RoktPaymentExtension`) is **not** proxied through Dart. Integrators must add the pod and register it directly from native Swift/Objective-C in the host app (for example `ios/Runner/AppDelegate.swift`), after `MParticle.sharedInstance().start(with:)`.

README.md

@@ -256,6 +256,58 @@ You must first call `getInstance` on `MparticleFlutterSdk` before each method is
 MparticleFlutterSdk? mpInstance = await MparticleFlutterSdk.getInstance();
 ```
 
+### Rokt
+
+`Rokt` is exposed under `mpInstance?.rokt` and supports:
+
+- `events(String identifier, void Function(dynamic event) onEvent)`
+- `selectPlacements(...)`
+- `selectShoppableAds(...)` (iOS implementation; Android no-op for parity; web unsupported)
+- `purchaseFinalized(...)` (iOS)
+
+Subscribe to events for a placement identifier before selecting placements:
+
+```dart
+mpInstance?.rokt.events('MSDKEmbeddedLayout', (event) {
+  print('Rokt event: $event');
+});
+
+await mpInstance?.rokt.selectPlacements(
+  identifier: 'MSDKEmbeddedLayout',
+  attributes: {'email': 'user@example.com'},
+);
+```
+
+For iOS shoppable ads:
+
+```dart
+mpInstance?.rokt.events('StgRoktShoppableAds', (event) {
+  print('Rokt shoppable event: $event');
+});
+
+await mpInstance?.rokt.selectShoppableAds(
+  identifier: 'StgRoktShoppableAds',
+  attributes: {'email': 'user@example.com'},
+);
+```
+
+To enable iOS payment flows for shoppable ads, add the payment extension pod in your app `ios/Podfile` and register it natively after `MParticle.sharedInstance().start(with:)`:
+
+```ruby
+pod 'RoktPaymentExtension'
+```
+
+```swift
+import RoktPaymentExtension
+
+if let paymentExtension = RoktPaymentExtension(
+  applePayMerchantId: "merchant.com.example.app",
+  urlScheme: nil
+) {
+  MParticle.sharedInstance().rokt.registerPaymentExtension(paymentExtension)
+}
+```
+
 ### Custom Events
 
 To log events, import mParticle `EventTypes` and `MPEvent` to write proper event logging calls: