Add exact Process selection and atomic column-slot group reorder

Preserve the full-desktop-1 captured source. Qualified previews inspect their exact subject read-only; group movement preserves source order and other columns. Native acceptance and strict-lint payload-size corrections follow separately.

crates/oa-desktop/src/app/process_canvas.rs

@@ -143,21 +143,11 @@ impl App {
                 }
             }
             CanvasEvent::SelectQualified(_, endpoint) => {
-                if !self.behavior.has_pending()
-                    && !self.draft_dirty()
-                    && !self.source_dirty()
-                    && let Ok(resolved) =
-                        oa_core::topology_context::TopologyIndex::new(self.project())
-                            .resolve(context.owner, &endpoint)
-                {
-                    let reference = endpoint
-                        .references
-                        .first()
-                        .copied()
-                        .unwrap_or(endpoint.occurrence);
-                    self.select(reference);
-                    self.behavior.topology.select_context(resolved.address);
-                }
+                self.multiselect_event(multiselect::Event::Choose(
+                    multiselect::process_context(context),
+                    crate::diagram_usage::Target::ProcessOccurrence(endpoint),
+                    multiselect::Choice::Replace,
+                ));
             }
             CanvasEvent::Select(_, id) => {
                 if !self.behavior.has_pending()
@@ -293,7 +283,8 @@ impl App {
                         occurrence, before, ..
                     } => {
                         match topology::reorder(self.project(), context.owner, occurrence, before) {
-                            Ok(command) => {
+                            Ok(topology::group_reorder::Plan::Noop) => {}
+                            Ok(topology::group_reorder::Plan::Change(command)) => {
                                 if self.execute(command) {
                                     self.selected = occurrence;
                                     self.refresh_draft();