Layouts reopen in the viewport they were saved in (#1670)

A save records the entered model viewport (or the sheet) as the layout's
last active viewport, and opening the layout enters it again with its
UCS. Picks up the codec fix that kept a last-active link from being read
as the sheet viewport (codec d57097c, kernel b40fa59, graph 2360341).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/update/file.rs

@@ -2196,6 +2196,12 @@ impl OpenCADStudio {
             self.tabs[i].scene.load_current_layout_state();
             self.tabs[i].refresh_active_ucs();
         }
+        // A layout saved with a model viewport entered reopens inside it,
+        // with that viewport's UCS (#1670).
+        let enter_viewport_task = self.tabs[i]
+            .scene
+            .saved_entered_viewport()
+            .map_or_else(Task::none, |handle| Task::done(Message::EnterViewport(handle)));
 
         // The tab may have been reused for the newly opened file. Any Plot
         // dialog cache belongs to the previous/startup drawing and must not
@@ -2317,6 +2323,7 @@ impl OpenCADStudio {
             interaction_task,
             startup_script_task,
             sheet_set_task,
+            enter_viewport_task,
         ])
     }
 
@@ -2640,6 +2647,7 @@ impl OpenCADStudio {
         if self.tabs[i].active_block_edit.is_none() {
             self.tabs[i].scene.sync_camera_to_document();
             self.tabs[i].last_synced_camera_gen = self.tabs[i].scene.camera_generation;
+            self.tabs[i].scene.sync_active_viewport_to_document();
         }
     }