chatgui: remember last read message, restore scroll position, show unread count badge

Store read/scroll positions per channel via ui_state table (key-value).
Draw red +N badge on channel list items for unread messages.
Fix getMessages() to fetch last N messages (was fetching first N).

tools/chatgui/src/mainwindow.cpp

@@ -212,6 +212,7 @@ void MainWindow::setupConnects() {
             this, [this](const QString& channelId) {
                 QSettings().setValue("last_channel_id", channelId);
                 m_currentChannelId = channelId;
+                m_channelList->setChannelUnreadCount(channelId, 0);
                 m_messageList->loadChannel(channelId);
                 m_accountList->setChannel(channelId);
                 QByteArray cidBA = channelId.toUtf8();
@@ -322,8 +323,15 @@ void MainWindow::showSettings() {
 void MainWindow::onMessageReceived(const char* ch_id) {
     DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "MainWindow: msg received ch=%s", ch_id);
     SoundManager::instance()->play("msg_incoming");
-    if (m_messageList)
-        m_messageList->refresh();
+    QString cid = QString::fromUtf8(ch_id);
+    if (m_messageList) {
+        if (cid == m_currentChannelId) {
+            m_messageList->refresh();
+        } else if (m_channelList) {
+            int unread = m_channelList->getChannelUnreadCount(cid) + 1;
+            m_channelList->setChannelUnreadCount(cid, unread);
+        }
+    }
 }
 
 void MainWindow::onMembersChanged(const char* ch_id) {