Dynamic dimensions: constant screen size, transform keeps the second constraint point

Every dynamic dimension gets a DIMSCALE override for 12 px text, refreshed
per zoom band, at creation and after load. A SCALE/ROTATE of an entity whose
own end points a driving dimension measures now pins its second constraint
point so the dimension moves the first end, as the reference does.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/app/command_driver.rs

@@ -3688,6 +3688,7 @@ impl OpenCADStudio {
                 );
                 // DYNCONSTRAINTDISPLAY 0 also keeps a new dynamic dimension off screen.
                 self.tabs[i].scene.refresh_hidden_dynamic_dimensions();
+                self.tabs[i].scene.refresh_dynamic_dimension_scales(true);
                 self.tabs[i].dirty = true;
                 self.tabs[i].active_cmd = None;
                 self.tabs[i].snap_result = None;