IMAGEADJUST: Image Adjust dialog for raster images

IMAGEADJUST (alias IAD) takes the selected raster images or asks
"Select image(s):", then opens a dialog with a before/after preview of
the first image and brightness, contrast and fade rows (bar plus
stepper, whole numbers 0-100). Apply writes the values to every chosen
image as one undo step; restore defaults sets 50/50/0. Adds the
image_adjust automation action and the image-adjust locale group.

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

src/app/update/mod.rs

@@ -9470,6 +9470,9 @@ impl OpenCADStudio {
                     let i = self.active_tab;
                     return self.run_dash_view("SETTINGS", i);
                 }
+                if self.active_modal == Some(super::ModalKind::ImageAdjust) {
+                    self.image_adjust = None;
+                }
                 if self.active_modal == Some(super::ModalKind::Field) {
                     self.close_field_dialog();
                     return Task::none();