Let the user choose what each folio editor toolbar holds

Configure QElectroTech > Toolbar contents: pick a toolbar, drag or add
commands from the list on the left, remove them with Delete, reorder,
add separators, and add, rename or delete toolbars of one's own.
Reset to defaults gives a toolbar its original contents back.

Each toolbar is stored as a list of command ids in QSettings
(diagrameditor/toolbars/<objectName>), the same pattern the shortcut
bar uses. A toolbar the user never changed stores nothing and is built
exactly as before; an id no command carries any more is skipped. The
four buttons that are widgets rather than commands (handle size, text
grid, background colour, conductor colour) get ids of their own and
can each be on one toolbar at a time. Stored scripts can go on any
toolbar.

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

sources/qetapp.cpp

@@ -43,6 +43,7 @@
 #include "ui/configpage/shortcutsconfigpage.h"
 #include "ui/configpage/shortcutbarconfigpage.h"
 #include "ui/configpage/toolbarsconfigpage.h"
+#include "ui/configpage/toolbarcommandsconfigpage.h"
 #include "machine_info.h"
 #include "TerminalStrip/ui/terminalstripeditorwindow.h"
 #include "qetversion.h"
@@ -2227,6 +2228,7 @@ void QETApp::configureQET()
 	cd.addPage(new ShortcutsConfigPage());
 	cd.addPage(new ShortcutBarConfigPage());
 	cd.addPage(new ToolbarsConfigPage());
+	cd.addPage(new ToolbarCommandsConfigPage());
 #ifdef QET_SPACEMOUSE_SUPPORT
 	cd.addPage(new SpaceMouseConfigPage());
 #endif