Tidy the free text width

- setTextWidth() returns without a signal when the width does not
  change, which is also the case on every load of a text without one.
- Say why IndependentTextItem::textWidth()/setTextWidth() hide the
  non-virtual QGraphicsTextItem functions, and what that means for code
  holding a base pointer.
- The fixture no longer carries a /tmp path from the machine it was
  made on.

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

sources/qetgraphicsitem/independenttextitem.cpp

@@ -130,6 +130,8 @@ void IndependentTextItem::setTextWidth(qreal width)
 {
 	if (!qIsFinite(width) || width <= 0)
 		width = -1;
+	if (qFuzzyCompare(width, m_text_width))
+		return;
 
 	qreal document_width = width;
 		//The automatic width of a text with centred or right-aligned

sources/qetgraphicsitem/independenttextitem.h

@@ -53,6 +53,11 @@ class IndependentTextItem : public DiagramTextItem
 		void setUuid(const QUuid &uuid) {m_uuid = uuid; emit uuidChanged();}
 		void newUuid() {setUuid(QUuid::createUuid());}	//create new uuid for this item
 
+			//Hide QGraphicsTextItem::textWidth()/setTextWidth(), which are not
+			//virtual: called through a QGraphicsTextItem or DiagramTextItem
+			//pointer they would change the document only, and the width would
+			//be neither saved nor shown in the properties. Use these, or the
+			//"textWidth" property.
 		qreal textWidth() const {return m_text_width;}
 		void setTextWidth(qreal width);