Feat: ZOOM IN/OUT/WINDOW commands; ZoomToWindow CmdResult

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/cmd_result.rs

@@ -356,6 +356,14 @@ impl H7CAD {
                     self.command_line.push_info(&p);
                 }
             }
+
+            CmdResult::ZoomToWindow { p1, p2 } => {
+                self.tabs[i].active_cmd = None;
+                self.tabs[i].snap_result = None;
+                self.tabs[i].scene.clear_preview_wire();
+                self.tabs[i].scene.zoom_to_window(p1, p2);
+                self.command_line.push_output("Zoom Window");
+            }
         }
         // Focus the command-line input while a command is active; blur it when the command ends.
         if self.tabs[i].active_cmd.is_some() {