Add global auto-numbering rules to QElectroTech settings

Add a 'Numérotation auto' tab to the global settings page (Settings >
Nouveau projet) where users can define default auto-numbering rules
for Conducteurs, Eléments, and Folios. These rules are automatically
transferred to every new project created.

Changes:
- Add NumerotationContext::saveToSettings()/loadFromSettings() static
  helpers for persisting named numerotation contexts via QSettings
- Add 'Numérotation auto' tab to NewDiagramPage with three sub-tabs
  using SelectAutonumW widgets (same UI as project properties)
- Add save/remove/persist slots for conductor, element, and folio
  contexts with immediate QSettings persistence on every change
- NewDiagramPage::applyConf() saves autonum settings when editing
  global defaults (no project)
- QETProject constructor loads global autonum settings from QSettings
  for new empty projects

sources/autoNum/numerotationcontext.cpp

@@ -275,3 +275,80 @@ QString NumerotationContext::formatValue(const QStringList &item)
 		return QString("%1").arg(value.toInt(), 3, 10, QChar('0'));
 	return QString::number(value.toInt());
 }
+
+/**
+	@brief NumerotationContext::saveToSettings
+	Save a hash of named NumerotationContexts to QSettings.
+	@param contexts : the named rules to save
+	@param currentRule : the name of the currently active rule
+	@param settings : QSettings instance
+	@param prefix : settings key prefix (e.g. "autonum/conductor")
+*/
+void NumerotationContext::saveToSettings(
+		const QHash<QString, NumerotationContext> &contexts,
+		const QString &currentRule,
+		QSettings &settings,
+		const QString &prefix)
+{
+	settings.setValue(prefix + "/current", currentRule);
+
+	// Clear stale array entries before writing (beginWriteArray does not
+	// remove entries beyond the new size).
+	settings.remove(prefix + "/rules");
+
+	QStringList names = contexts.keys();
+	settings.beginWriteArray(prefix + "/rules", names.size());
+	for (int i = 0; i < names.size(); ++i) {
+		settings.setArrayIndex(i);
+		const QString &name = names.at(i);
+		const NumerotationContext &nc = contexts.value(name);
+
+		settings.setValue("name", name);
+
+		// Serialize context to XML string
+		QDomDocument doc;
+		NumerotationContext nc_copy = nc;
+		QDomElement root = nc_copy.toXml(doc, "context");
+		doc.appendChild(root);
+		settings.setValue("xml", doc.toString());
+	}
+	settings.endArray();
+}
+
+/**
+	@brief NumerotationContext::loadFromSettings
+	Load named NumerotationContexts from QSettings.
+	@param settings : QSettings instance
+	@param prefix : settings key prefix (e.g. "autonum/conductor")
+	@return pair of (hash of named rules, name of current rule)
+*/
+QPair<QHash<QString, NumerotationContext>, QString> NumerotationContext::loadFromSettings(
+		QSettings &settings,
+		const QString &prefix)
+{
+	QPair<QHash<QString, NumerotationContext>, QString> result;
+	QHash<QString, NumerotationContext> &contexts = result.first;
+	QString &currentRule = result.second;
+
+	currentRule = settings.value(prefix + "/current").toString();
+
+	int size = settings.beginReadArray(prefix + "/rules");
+	for (int i = 0; i < size; ++i) {
+		settings.setArrayIndex(i);
+		QString name = settings.value("name").toString();
+		QString xmlStr = settings.value("xml").toString();
+
+		if (name.isEmpty() || xmlStr.isEmpty()) continue;
+
+		QDomDocument doc;
+		if (!doc.setContent(xmlStr)) continue;
+
+		QDomElement root = doc.documentElement();
+		NumerotationContext nc;
+		nc.fromXml(root);
+		contexts.insert(name, nc);
+	}
+	settings.endArray();
+
+	return result;
+}

sources/autoNum/numerotationcontext.h

@@ -21,6 +21,8 @@
 #include <QStringList>
 #include <QVariant>
 #include <QDomElement>
+#include <QHash>
+#include <QSettings>
 
 /**
 	This class represents a numerotation context, i.e. the data (type, value, increase)
@@ -60,6 +62,14 @@ class NumerotationContext
 		/// UI preview of a part's value matches what actually gets rendered.
 	static QString formatValue(const QStringList &item);
 
+	static void saveToSettings(const QHash<QString, NumerotationContext> &contexts,
+				   const QString &currentRule,
+				   QSettings &settings,
+				   const QString &prefix);
+	static QPair<QHash<QString, NumerotationContext>, QString> loadFromSettings(
+				   QSettings &settings,
+				   const QString &prefix);
+
 	private:
 	QStringList content_;
 };