Add %T, the target folio's title, to report and cross reference formulas

A folio report could name the folio it points to by position (%f), folio
number (%F), installation (%M) and location (%LM), but not by its title.
EPLAN and other tools print references like "+UV1/1 Versorgung UG/EG.0",
which with %T is the formula "+%LM/%F %T.%c".

- FormulaContext carries the folio title, filled from the title block.
- %T is replaced on its own only, not as the start of a longer word.
- A report whose formula uses %T follows the target folio's title block
  (BorderTitleBlock::informationChanged), as %F already follows its
  folio number.
- The report and cross reference property pages list %T.

tst_reportfoliotitle checks the replacement, that %total and title
block variables keep their values, and an empty title.

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

sources/autoNum/assignvariables.h

@@ -69,6 +69,8 @@ namespace autonum
 	{
 			/// border_and_titleblock.folio(), folioIndex(), folioTotal()...
 		QString folio;
+			/// the folio's title, %T
+		QString folio_title;
 		int folio_index = 0;
 		int folio_total = 0;
 		QString plant;