4 backports to do

main	13.4	12.4
Merged #87515 [BUGFIX] Update CKEditor model in source edit view on input Author Benjamin Franzke Updated 03/04/25, 18:48 Affected Files 2 Patchsets 10 Reviews 3 Verifies 3	Merged #88480 [BUGFIX] Update CKEditor model in source edit view on input 13.4 Author Benjamin Franzke Updated 03/04/25, 18:48 Affected Files 2 Patchsets 2 Reviews 2 Verifies 2	#90840 [BUGFIX] Update CKEditor model in source edit view on input 12.4 Author Andreas Kienast Updated 09/30/25, 08:54 Affected Files 2 Patchsets 2 Reviews Verifies
Merged #87976 [BUGFIX] Handle file upload validation for empty argument Author Georg Ringer Updated 10/31/25, 11:28 Affected Files 2 Patchsets 4 Reviews 4 Verifies 4	Review is missing.
Merged #88586 [BUGFIX] Properly check for sub schema Author Georg Ringer Updated 10/31/25, 13:19 Affected Files 1 Patchsets 2 Reviews 3 Verifies 3	Review is missing.
Merged #91581 [TASK] Live documentation for changelog and manuals Author Garvin Hicking Updated 11/15/25, 09:18 Affected Files 5 Patchsets 4 Reviews 5 Verifies 5	Review is missing.	Review is missing.