Live mode: an AI assistant acts on the open project while the user watches

A new setting, Configurer QElectroTech > Général > "Autoriser un assistant
IA à agir sur le projet ouvert", off by default. Off, nothing changes:
no channel is opened. On, every start shows a warning first -- Continuer,
Pas pour cette session, or Désactiver -- and nothing can connect until
the user answers Continuer. It waits for any other start-up question to
be answered, so the two never stack.

Accepted, LiveServer opens a local socket only the user's account can
use, with a random name and token written to live-session.json in the
data folder for the qet MCP server, and removed when the channel closes.
One JSON request per line: status (project, folio on screen, selection,
last undo step, stored scripts), run_script and run_stored. Requests are
queued out of the socket handler before they run (the lesson of PR #861).

Each run is one undo step named "Assistant : <name>". The status bar
shows the mode and the assistant's last action with a ✓ or ✗ and the
time, and an Arrêter button that closes the channel for the session.
Unticking the setting closes it at once.

QetScripting::runSource() runs script text and, for a live run, returns
what qet.log() wrote, the error with its line and the undo step instead
of showing boxes; qet.showMessage() is logged rather than opening a box
nobody asked for.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sources/scripting/liveserver.h

@@ -0,0 +1,93 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef LIVESERVER_H
+#define LIVESERVER_H
+
+#include <QJsonObject>
+#include <QObject>
+#include <QPointer>
+
+class QLocalServer;
+class QLocalSocket;
+class QETDiagramEditor;
+class QWidget;
+
+/**
+	@brief The LiveServer class
+	Live mode: an AI assistant, through the qet MCP server, runs scripts on
+	the project open in this QElectroTech while the user watches.
+
+	Three things must all be true before anything can connect: scripting is
+	allowed, the "mode direct" setting is on (off by default), and the user
+	accepted the warning shown at this start. With the setting off this
+	class opens nothing and QElectroTech behaves as if it did not exist.
+
+	The channel is a QLocalServer only the user's own account can open,
+	with a random name and token written to live-session.json in the data
+	folder, which the MCP server reads; the file goes when the channel
+	closes. One request per line, one answer per line, both JSON; every
+	request carries the token.
+
+	Requests are never handled inside the socket's readyRead: each is
+	queued to the event loop first. QETApp::receiveMessage() learnt why --
+	a modal dialog opened from inside a socket handler crashed QElectroTech
+	once the socket went away (PR #861).
+*/
+class LiveServer : public QObject
+{
+	Q_OBJECT
+
+	public:
+		enum State { Off, Waiting, Connected };
+
+		static LiveServer &instance();
+		static QString sessionFile();
+
+		void askAndStart(QWidget *parent);
+		void stop();
+		State state() const { return m_state; }
+
+	signals:
+		void stateChanged(LiveServer::State state);
+			/// A request was handled: what was asked, and the answer sent
+		void handled(const QJsonObject &request, const QJsonObject &answer);
+
+	private:
+		LiveServer();
+		~LiveServer() override;
+		bool start();
+		void setState(State state);
+		void newConnection();
+		void readClient();
+		void handle(const QJsonObject &request);
+		void send(const QJsonObject &answer);
+		QJsonObject status();
+		QJsonObject runScript(const QString &name, const QString &source);
+		QJsonObject runStored(const QString &id);
+		QETDiagramEditor *editor() const;
+
+		QLocalServer *m_server = nullptr;
+		QPointer<QLocalSocket> m_client;
+		QByteArray m_buffer;
+		QString m_token;
+		State m_state = Off;
+		bool m_asked = false;
+		bool m_busy = false;
+};
+
+#endif // LIVESERVER_H