terminaldata: add No, Nc, Common types for SW contacts

Extend TerminalData::Type enum with three new semantic values:
- No     : Normally Open terminal of a switch (SW) contact
- Nc     : Normally Closed terminal of a switch (SW) contact
- Common : Common terminal of a switch (SW) contact

Update typeToString() and typeFromString() accordingly.
Fully backward compatible: existing Generic/Inner/Outer types
are unchanged. Elements without typed terminals fall back
to the previous behavior (first 2 named terminals).

terminal: expose terminalType() as public accessor

Add Terminal::terminalType() returning the TerminalData::Type
of this terminal. This allows crossrefitem and other consumers
to filter terminals by semantic role (No, Nc, Common) without
accessing TerminalData internals directly.

terminaleditor: add No, Nc, Common entries to type combobox

Expose the three new TerminalData types (No, Nc, Common) in
the element editor UI so users can assign a semantic role to
each terminal of a SW contact element.

Also fix a pre-existing bug in updateForm() where m_type_cb
was incorrectly using m_orientation_cb->findData() instead
of m_type_cb->findData(), preventing the type from being
restored correctly when selecting a terminal.

terminaleditor: add No, Nc, Common entries to type combobox

Expose the three new TerminalData types (No, Nc, Common) in
the element editor UI so users can assign a semantic role to
each terminal of a SW contact element.

Also fix a pre-existing bug in updateForm() where m_type_cb
was incorrectly using m_orientation_cb->findData() instead
of m_type_cb->findData(), preventing the type from being
restored correctly when selecting a terminal.

sources/qetgraphicsitem/terminal.h

@@ -18,13 +18,14 @@
 #ifndef TERMINAL_H
 #define TERMINAL_H
 #include "../qet.h"
+#include "../properties/terminaldata.h"
 
 #include <QtWidgets>
 #include <QtXml>
 class Conductor;
 class Diagram;
 class Element;
-class TerminalData;
+
 
 /**
 	@brief The Terminal class
@@ -75,6 +76,7 @@ class Terminal : public QGraphicsObject
 		Element  *parentElement       () const;
 		QUuid     uuid                () const;
 		QString   name                () const;
+		TerminalData::Type terminalType() const;
 
 		QList<Conductor *> conductors() const;
 		Qet::Orientation orientation() const;