Add pendingPublishRelaysFor stub to desktopApp StubNostrClient

Add pendingPublishRelaysFor stub to test NostrClient fakes

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nip46RemoteSigner/signer/NostrSignerRemoteIsolationTest.kt

@@ -88,6 +88,8 @@ private class TrackingNostrClient : INostrClient {
         sentEvents.add(event to relayList)
     }
 
+    override fun pendingPublishRelaysFor(eventId: String): Set<NormalizedRelayUrl>? = null
+
     override fun addConnectionListener(listener: RelayConnectionListener) {}
 
     override fun removeConnectionListener(listener: RelayConnectionListener) {}

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nip46RemoteSigner/signer/RemoteSignerManagerRetryTest.kt

@@ -207,6 +207,8 @@ private class CountingNostrClient(
         onPublish()
     }
 
+    override fun pendingPublishRelaysFor(eventId: String): Set<NormalizedRelayUrl>? = null
+
     override fun addConnectionListener(listener: RelayConnectionListener) {}
 
     override fun removeConnectionListener(listener: RelayConnectionListener) {}