feat(statusbar): isolate / hide objects with status pill

Add a hidden-entity set to the scene that the tessellation visibility
test skips, so hidden objects neither render nor hit-test. New commands
ISOLATEOBJECTS (show only the selection), HIDEOBJECTS (hide the
selection) and UNISOLATEOBJECTS (restore). An ISO status pill lights up
while anything is hidden and restores everything on click.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/commands.rs

@@ -332,6 +332,44 @@ impl OpenCADStudio {
                 }
             }
 
+            // ISOLATEOBJECTS — hide every object except the current selection
+            "ISOLATEOBJECTS" => {
+                if self.tabs[i].scene.selected.is_empty() {
+                    self.command_line
+                        .push_error("ISOLATEOBJECTS: select the objects to isolate first.");
+                } else {
+                    let n = self.tabs[i].scene.selected.len();
+                    self.tabs[i].scene.isolate_selected();
+                    self.command_line.push_info(&format!(
+                        "Isolated {n} object(s). UNISOLATEOBJECTS to restore."
+                    ));
+                }
+            }
+
+            // HIDEOBJECTS — hide the current selection
+            "HIDEOBJECTS" => {
+                if self.tabs[i].scene.selected.is_empty() {
+                    self.command_line
+                        .push_error("HIDEOBJECTS: select the objects to hide first.");
+                } else {
+                    let n = self.tabs[i].scene.selected.len();
+                    self.tabs[i].scene.hide_selected();
+                    self.command_line
+                        .push_info(&format!("Hid {n} object(s). UNISOLATEOBJECTS to restore."));
+                }
+            }
+
+            // UNISOLATEOBJECTS — bring back everything hidden by Isolate / Hide
+            "UNISOLATEOBJECTS" => {
+                if self.tabs[i].scene.is_isolation_active() {
+                    self.tabs[i].scene.end_isolation();
+                    self.command_line
+                        .push_info("Isolation ended — all objects shown.");
+                } else {
+                    self.command_line.push_info("No hidden objects.");
+                }
+            }
+
             // LAYUNISO — restore all layers that were turned off by LAYISO (turn all on)
             "LAYUNISO" => {
                 self.push_undo_snapshot(i, "LAYUNISO");

src/app/view.rs

@@ -1159,6 +1159,7 @@ impl OpenCADStudio {
                         self.clean_screen,
                         tab.scene.document.header.insertion_units,
                         self.units_popup_open,
+                        tab.scene.is_isolation_active(),
                         &self.statusbar_config,
                     )
                 })