Reconcile orphaned Design View snapshots on track delete

Add ViewModeModel::reconcile(liveGuids) to prune snapshots of deleted
tracks; wire it into applyMode before planning. Keep membership so
undo-delete (same GUID) preserves the Design tag.

src/view.cpp

@@ -144,6 +144,16 @@ bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject
     std::vector<TrackFolderEntry> entries = readFolderEntries(proj, handleByGuid);
     FolderTree tree = buildFolderTree(entries);
 
+    // Reconcile orphaned model state BEFORE planning: prune snapshots whose track was
+    // deleted from the project (its GUID no longer appears in the live enumeration).
+    // handleByGuid holds every currently-enumerated track GUID, so its keys are the
+    // authoritative live set. Membership is intentionally NOT pruned (undo-delete
+    // restores the same GUID — see ViewModeModel::reconcile). Because reapply-on-load
+    // routes through applyMode, this also reconciles on project open.
+    std::set<std::string> liveGuids;
+    for (const auto& kv : handleByGuid) liveGuids.insert(kv.first);
+    model.reconcile(liveGuids);
+
     TogglePlan plan = model.planToggle(tree, targetModeId);
 
     Undo_BeginBlock2(proj);