fix(ads): pass the rewarded ad's nonce through to connect

With ads enabled the SSV nonce and the nonce the connect flow waited for
were minted separately, so the client rejected the very session the ad had
just created and failed with "Session not activated".

- showAd() returns the nonce it put in the SSV custom_data (null on no reward)
- fetchConfigDirectly({adNonce, resume}) replaces skipAdBypass: a real ad
  waits for exactly that nonce and polls ~36 s for Google's callback, the
  bypass path mints its own, and resume re-attaches to the session the
  device already owns
- SOCKS5 "Reconnect" uses resume: true instead of requesting a new session

Co-Authored-By: Claude Opus 5 <[email protected]>

lib/logic/ad_manager.dart

@@ -1,6 +1,5 @@
 import 'dart:async';
 import 'dart:convert';
-import 'dart:math';
 import 'package:flutter/foundation.dart';
 import 'package:google_mobile_ads/google_mobile_ads.dart';
 import 'package:revoltvpn/logic/crypto_service.dart';
@@ -97,13 +96,20 @@ class AdManager extends ChangeNotifier {
 
   // ── Show ad (or debug bypass) ─────────────────────────────────────
 
-  Future<bool> showAd(String adType) async {
-    // Debug bypass: fire fake AdMob callback so support ads work in dev.
-    // The server's ADMOB_BYPASS must be True for this to succeed.
-    if (!adsEnabled && kDebugMode) {
+  // Returns the nonce carried in the SSV custom_data when the reward was
+  // earned, null otherwise. The main flow passes it to vpn.connect(adNonce:)
+  // so the client waits for the session this ad created — minting a second
+  // nonce there is what broke every connect once ads were on.
+  Future<String?> showAd(String adType) async {
+    if (!adsEnabled) {
+      // Main connect: no ad to show — HivemindService.fetchConfigDirectly()
+      // fires the server-gated bypass itself (rule 87).
+      if (adType != 'support' || !kDebugMode) return null;
+
+      // Debug bypass: fire fake AdMob callback so support ads work in dev.
+      // The server's ADMOB_BYPASS must be True for this to succeed.
       final deviceId = await CryptoService.getDeviceId();
-      final nonce = '${Random().nextInt(0x7FFFFFFF)}-${DateTime.now().millisecondsSinceEpoch}';
-      HivemindService.setExpectedNonce(nonce);
+      final nonce = HivemindService.newNonce();
       try {
         final customData = jsonEncode({
           'device_id': deviceId,
@@ -115,29 +121,24 @@ class AdManager extends ChangeNotifier {
             '?signature=test&key_id=test'
             '&custom_data=${Uri.encodeComponent(customData)}');
         await HivemindService.directGet(fakeUrl, timeout: const Duration(seconds: 8));
-        return true;
+        return nonce;
       } catch (_) {
-        return false;
+        return null;
       }
     }
 
-    if (!adsEnabled) return false;
-
     await ensureSdkInitialized();
 
     if (!_isAdLoaded || _rewardedAd == null) {
       final loaded = await preloadAd();
       if (!loaded || _rewardedAd == null) {
         debugPrint('[AdManager] Cannot show ad, failed to load.');
-        return false;
+        return null;
       }
     }
 
     final deviceId = await CryptoService.getDeviceId();
-
-    final nonce = '${Random().nextInt(0x7FFFFFFF)}-${DateTime.now().millisecondsSinceEpoch}';
-    HivemindService.setExpectedNonce(nonce);
-    debugPrint('[AdManager] Ad nonce: $nonce');
+    final nonce = HivemindService.newNonce();
 
     final ssvOptions = ServerSideVerificationOptions(
       customData: jsonEncode({
@@ -182,7 +183,7 @@ class AdManager extends ChangeNotifier {
       },
     );
 
-    return rewardCompleter.future;
+    return await rewardCompleter.future ? nonce : null;
   }
 
   @override