Assistant house style: a drawing-convention text every AI assistant reads

QetSettings::houseStyle()/setHouseStyle() (assistant/house_style),
qet.houseStyle()/qet.setHouseStyle() in the script API, a house_style
field in qet-assistant.json, and qet_about in the qet MCP server
showing it.

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

sources/scripting/qetscriptapi.cpp

@@ -44,6 +44,7 @@
 #include "../conductorsegment.h"
 #include "../conductorrouter.h"
 #include "../qetgraphicsitem/diagramimageitem.h"
+#include "../utils/qetsettings.h"
 
 // See diagrameventaddpdf.h: a missing QtPdf module (or Qt < 6.4) is not
 // fatal at build time, so addPdfPage() is always declared -- a script
@@ -4200,6 +4201,32 @@ QStringList QetScriptApi::folioPresets() const
 	return names;
 }
 
+/**
+	@brief QetScriptApi::houseStyle
+	This installation's drawing conventions (grid, flow direction, routing,
+	tagging, grouping, ...), as free text the user wrote once. Empty when
+	nobody has set any. Not project-scoped: the same text for every
+	project this QElectroTech opens, same as liveAssistantEnabled().
+	@return the text
+*/
+QString QetScriptApi::houseStyle() const
+{
+	return QetSettings::houseStyle();
+}
+
+/**
+	@brief QetScriptApi::setHouseStyle
+	Write the installation's drawing conventions. Always succeeds (a plain
+	setting, not project data, so there is nothing here to refuse); @return
+	is for a consistent call shape with the rest of the API.
+	@param text
+*/
+bool QetScriptApi::setHouseStyle(const QString &text)
+{
+	QetSettings::setHouseStyle(text);
+	return true;
+}
+
 /**
 	@brief QetScriptApi::setFolioBorder
 	Change one field of a folio's frame through ChangeBorderCommand, as the