feat(xref): reference list with stale and orphaned status detection

Reference list rows showing stale and orphaned states with handle-based identity.

src/app/view/modal.rs

@@ -20,6 +20,8 @@ impl OpenCADStudio {
             Some(K::UpdateNotice) => crate::tr!("modal", "update-available"),
             Some(K::DonationPrompt) => crate::tr!("donation", "title"),
             Some(K::Layers) => crate::tr!("modal", "layer-manager"),
+            // XREF-Task8: locale (hardcoded until Task 8 batches locale strings).
+            Some(K::XrefManager) => "Reference Manager".to_string(),
             Some(K::LayerStateManager) => crate::tr!("modal", "layer-state-manager"),
             Some(K::LayerTranslator) => crate::t!("Layer Translator").into_owned(),
             Some(K::DrawingUnits) => crate::t!("Drawing Units").into_owned(),
@@ -394,6 +396,11 @@ impl OpenCADStudio {
                     |flow| tab.layers.view_window(self.layer_name_col_w, flow),
                 )
             }
+            super::super::ModalKind::XrefManager => {
+                sized_flow(ex, 960, 520, |flow| {
+                    self.xref_manager.view_window(flow)
+                })
+            }
             super::super::ModalKind::LayerTranslator => {
                 use crate::modules::draw::layers::laytrans;
                 let i = self.active_tab;