fix(billing): mark Freedom purchased BEFORE acknowledgePurchase async call

THE ACTUAL BUG (post-purchase flow):

When the user completes the Freedom purchase in the Play Billing sheet:
1. purchasesUpdatedListener fires → handlePurchase() is called
2. OLD CODE: markAsFreedomPurchased() was called only INSIDE the
   acknowledgePurchase() async callback — i.e. after Google's server
   round-trip (can take 1-3+ seconds)
3. MEANWHILE: onResume() fires as the app returns from the billing sheet
   → loadWebViewContent() reloads the WebView
   → queryActiveSubscriptions() runs concurrently
4. The freshly loaded WebView calls isFreedomPurchased() at DOMContentLoaded
   → SharedPrefs still says FALSE (markAsFreedomPurchased not called yet)
   → shows BUY BUTTONS instead of the Freedom confirmation card
5. queryActiveSubscriptions() may also return an empty list at this point
   → clears the mark (before today's 5s-delay fix) or does nothing wrong
6. Only AFTER acknowledgePurchase completes does markAsFreedomPurchased()
   run — but the WebView has already rendered the wrong state and the
   JS callback either landed on the wrong page state or got lost

FIX: Move markAsFreedomPurchased(), markAsPurchased(), updateTrialState()
and evaluateWebViewJsWithRetry(true) to BEFORE the isAcknowledged check,
so SharedPreferences is updated synchronously the instant purchaseState
== PURCHASED is confirmed. The async acknowledgePurchase() only handles
the server-side ack step now; it no longer gates any UI update.

Author: Claude Bot

app/src/main/kotlin/com/google/ai/sample/MainActivity.kt

@@ -1255,6 +1255,14 @@ class MainActivity : ComponentActivity() {
             Log.d(TAG, "handlePurchase: Purchase state is PURCHASED.")
             if (MainActivityBillingStateEvaluator.containsSubscriptionProduct(purchase, freedomProductId)) {
                 Log.d(TAG, "handlePurchase: Purchase contains Freedom product ID: $freedomProductId")
+                // Mark as purchased IMMEDIATELY (before acknowledgement) so that any concurrent
+                // queryActiveSubscriptions() or WebView reload already sees the correct state.
+                // purchaseState == PURCHASED already confirms the payment; acknowledgement is
+                // just a server-side confirmation step that must not gate the UI update.
+                TrialManager.markAsFreedomPurchased(this)
+                TrialManager.markAsPurchased(this)
+                updateTrialState(TrialManager.getTrialState(this, null))
+                evaluateWebViewJsWithRetry("window.onFreedomPurchaseStateChanged && window.onFreedomPurchaseStateChanged(true)")
                 if (!purchase.isAcknowledged) {
                     Log.i(TAG, "handlePurchase: Purchase not acknowledged. Acknowledging now.")
                     val acknowledgePurchaseParams = AcknowledgePurchaseParams.newBuilder()
@@ -1265,11 +1273,6 @@ class MainActivity : ComponentActivity() {
                         if (ackBillingResult.responseCode == BillingClient.BillingResponseCode.OK) {
                             Log.i(TAG, "Freedom subscription purchase acknowledged successfully.")
                             updateStatusMessage("Thank you for your Freedom subscription!")
-                            TrialManager.markAsFreedomPurchased(this)
-                            TrialManager.markAsPurchased(this)
-                            updateTrialState(TrialManager.getTrialState(this, null))
-                            evaluateWebViewJsWithRetry("window.onFreedomPurchaseStateChanged && window.onFreedomPurchaseStateChanged(true)")
-                            Log.d(TAG, "handlePurchase Freedom: Stopping TrialTimerService.")
                             val stopIntent = Intent(this, TrialTimerService::class.java)
                             stopIntent.action = TrialTimerService.ACTION_STOP_TIMER
                             startService(stopIntent)
@@ -1281,10 +1284,9 @@ class MainActivity : ComponentActivity() {
                 } else {
                     Log.i(TAG, "handlePurchase: Freedom subscription already acknowledged.")
                     updateStatusMessage("Freedom subscription already active.")
-                    TrialManager.markAsFreedomPurchased(this)
-                    TrialManager.markAsPurchased(this)
-                    updateTrialState(TrialManager.getTrialState(this, null))
-                    evaluateWebViewJsWithRetry("window.onFreedomPurchaseStateChanged && window.onFreedomPurchaseStateChanged(true)")
+                    val stopIntent = Intent(this, TrialTimerService::class.java)
+                    stopIntent.action = TrialTimerService.ACTION_STOP_TIMER
+                    startService(stopIntent)
                 }
             } else if (MainActivityBillingStateEvaluator.containsSubscriptionProduct(purchase, subscriptionProductId)) {
                 Log.d(TAG, "handlePurchase: Purchase contains target product ID: $subscriptionProductId")