As part of rB3f91540cef7e, we already made `OB_MODE_SCULPT_CURVES` to be allowed in `paint_curve_poll` (alongside `OB_MODE_ALL_PAINT`). Now, to get the paintcurves transform systems to work with curves sculptmode as well, we introduce this "additional case" in the appropriate place in the transform system as well. NOTE: as a next step, considering `OB_MODE_SCULPT_CURVES` to be generally part of `OB_MODE_ALL_PAINT` is to be done (this might fix another couple of bugs, but also has to be carefully checked in many places, so this patch is just fixing this very specific case) Fixes T102204. Maniphest Tasks: T102204 Differential Revision: https://developer.blender.org/D16466