fixed stale state after logout and replayed or lost share intents

lib/push/push_registration.dart

@@ -107,6 +107,7 @@ class PushRegistration {
   /// fire-and-forget (and simply ignore the result).
   Future<bool> register() async {
     if (DemoMode.active) return false;
+    final epoch = AccountData().sessionEpoch;
     final String? fcmToken;
     try {
       fcmToken = await FirebaseMessaging.instance.getToken();
@@ -159,6 +160,7 @@ class PushRegistration {
         fcmToken: fcmToken,
         pems: pems,
         appVersion: appVersion,
+        epoch: epoch,
       );
       allOk = allOk && ok;
     }
@@ -170,6 +172,7 @@ class PushRegistration {
     required String fcmToken,
     required PushKeypairPems pems,
     required String? appVersion,
+    required int epoch,
   }) async {
     try {
       final proxyServer = currentProxyServer;
@@ -185,6 +188,11 @@ class PushRegistration {
         userAgent: isTalk ? _talkUserAgent : null,
       );
 
+      // Signed out while registering: persisting or announcing this
+      // registration would keep delivering the previous account's pushes,
+      // and logoutCleanup already ran so nothing would unregister it.
+      if (!AccountData().isCurrentSession(epoch)) return false;
+
       await _store.save(
         type: type,
         deviceIdentifier: registration.deviceIdentifier,