WIP: Sheet Set Manager palette, wizard, properties and sheet set fields

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

src/app/update/mod.rs

@@ -1819,6 +1819,7 @@ impl OpenCADStudio {
             Message::AttdefDialog(message) => self.on_attdef_dialog(message),
             Message::FieldDialog(message) => self.on_field_dialog(message),
             Message::PcManager(message) => self.update_pc_manager(message),
+            Message::SheetSet(message) => self.on_sheet_set(message),
             Message::RibbonSelectTab(idx) => {
                 self.ribbon.select(idx);
                 Task::none()
@@ -8521,6 +8522,10 @@ impl OpenCADStudio {
             }
 
             Message::CloseModal => {
+                if self.active_modal == Some(super::ModalKind::SheetSet) {
+                    self.close_sheet_set_dialog();
+                    return Task::none();
+                }
                 if self.active_modal == Some(super::ModalKind::Field) {
                     self.close_field_dialog();
                     return Task::none();