gui: auto-switch to newly created agent, remove remote field from agent dialog

createAgent now returns the new agent ID so the dialog can immediately
switch to it. Previously the first agent created required a GUI restart
to select.

Also removes the Remote field from NewAgentDialog — remote belongs to
the session, not the agent.

gui/NewAgentDialog.qml

@@ -103,16 +103,6 @@ Dialog {
             }
         }
 
-        RowLayout {
-            Layout.fillWidth: true
-            Label { text: "Remote:"; Layout.preferredWidth: 80 }
-            TextField {
-                id: remoteField
-                Layout.fillWidth: true
-                placeholderText: "user@host:port"
-            }
-        }
-
         Component.onCompleted: {
             if (!ollie.rootBackendsLoaded) ollie.loadRootBackends()
             if (!ollie.rootAgentsLoaded) ollie.loadRootAgents()
@@ -151,12 +141,14 @@ Dialog {
                 var backend = backendCombo.currentText.trim()
                 var model = modelCombo.currentIndex >= 0 ? modelCombo.currentText.trim() : ""
                 var agent = agentCombo.currentText
-                var remote = remoteField.text.trim()
                 var agentAlias = aliasField.text.trim()
 
-                var err = ollie.createAgent(root.targetSessionId, cwd, backend, model, agent, remote, agentAlias)
+                var newAgentId = ollie.createAgent(root.targetSessionId, cwd, backend, model, agent, "", agentAlias)
+                var err = ollie.lastError()
                 if (err === "") {
+                    // Success: refresh then switch to the newly created agent.
                     ollie.refreshSessions()
+                    ollie.switchAgent(root.targetSessionId, newAgentId)
                     root.agentCreated()
                     root.close()
                 } else {

gui/ollie9pclient.cpp

@@ -587,7 +587,9 @@ QString Ollie9pClient::createAgent(const QString &sessionId, const QString &cwd,
         qDebug() << "createAgent failed:" << err;
         return err;
     }
-    return QString();
+    // Return the new agent's ID (trimmed) so callers can switch to it immediately.
+    // Format: "agentid\n"
+    return QString::fromUtf8(result).trimmed();
 }
 
 bool Ollie9pClient::killAgent(const QString &sessionId, const QString &agentId)

gui/ollie9pclient.h

@@ -85,6 +85,7 @@ public:
     Q_INVOKABLE bool killAgent(const QString &sessionId, const QString &agentId);
     Q_INVOKABLE bool renameSession(const QString &sessionId, const QString &newName);
     Q_INVOKABLE bool renameAgent(const QString &sessionId, const QString &agentId, const QString &newName);
+    Q_INVOKABLE QString lastError() const { return m_9p ? m_9p->lastError() : QString(); }
 
 signals:
     void sessionsChanged();