fix(chatgui): remove duplicate loadChannels after JoinDialog close, remove 800ms delay

- showJoinDialog: don't call loadChannels after dialog close — channel already in model via CHANNEL_UPDATED event, online badge via CHANNEL_PEERS_ONLINE. Duplicate loadChannels was resetting the peer online count.
- onConnectResult: remove 800ms QTimer — dialog closes immediately. Channel data arrives independently through the event pipeline.

tools/chatgui/src/joindialog.cpp

@@ -195,12 +195,10 @@ void JoinDialog::onConnectResult(uint64_t nodeId, uint64_t channelId, int result
     if (!m_connecting || nodeId != m_pendingNodeId) return;
 
     if (result == 0) {
-        setStatus("Connected! Waiting for channel data...");
-        QTimer::singleShot(800, this, [this] {
-            QString cid = QString::number(m_pendingChannelId);
-            emit joined(cid);
-            accept();
-        });
+        setStatus("Connected!");
+        QString cid = QString::number(m_pendingChannelId);
+        emit joined(cid);
+        accept();
     } else {
         m_connecting = false;
         m_connectBtn->setEnabled(true);