feat(render): logical style metrics with a UI scale, so chrome has a consistent physical size

adapters/imgui/imgui_plot.cpp

@@ -119,6 +119,11 @@ void PlotWidget::draw(const char* id, Plot& plot, Vec2 size, Renderer& renderer)
     controller_->set_viewport(region);
     forward_input(hovered);
 
+    // The backend's framebuffer scale is the display's scale, so the renderer draws
+    // its logical style metrics at it: the same assertion above pins it positive,
+    // and the chrome is then the same physical size whatever surface the host
+    // renders into.
+    renderer.style().ui_scale = scale.x;
     const u32 fb_w = static_cast<u32>(fb_w_f + 0.5f);
     const u32 fb_h = static_cast<u32>(fb_h_f + 0.5f);
     renderer.begin_frame(fb_w, fb_h, region);