View backgrounds: image colours as stored, viewport style name, adjust automation

- The background image texture is not an sRGB view: the image is drawn with
  its own colours, as the solid and gradient colours are.
- An entered paper-space viewport shows its named visual style (Realistic,
  ...) in the render-mode picker, and a mode picked there is recorded as the
  viewport's visual style.
- The view_background automation action takes offset=x,y and scale=x,y.

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

src/app/view/mod.rs

@@ -182,6 +182,24 @@ impl std::fmt::Display for RenderModeChoice {
     }
 }
 
+/// A named style (Realistic, …) the active viewport draws as, by name.
+fn named_visual_style(
+    scene: &crate::scene::Scene,
+    mode: codec::entities::ViewportRenderMode,
+) -> Option<String> {
+    match scene.document.objects.get(&scene.active_visual_style()) {
+        Some(codec::objects::ObjectType::VisualStyle(style)) => {
+            match crate::modules::view::visual_style::mode_for_style_name(&style.description) {
+                Some((named_mode, true)) if named_mode == mode => {
+                    Some(crate::t!(style.description.as_str()).into_owned())
+                }
+                _ => None,
+            }
+        }
+        _ => None,
+    }
+}
+
 impl OpenCADStudio {
     #[cfg(not(target_arch = "wasm32"))]
     pub fn view(&self, window_id: window::Id) -> Element<'_, Message> {
@@ -1297,18 +1315,7 @@ bg={bg_ms:.1}ms n={view_count}"
                 let rect = tab.scene.active_model_tile_bounds(vw, vh);
                 // Unified control chip: split buttons + render-mode picker +
                 // grid / grid-snap toggles, for the active Model tile.
-                // A named style (Realistic, …) the tile draws as shows by name.
-                let style_name = match tab.scene.document.objects.get(&tab.scene.active_visual_style()) {
-                    Some(codec::objects::ObjectType::VisualStyle(style)) => {
-                        match crate::modules::view::visual_style::mode_for_style_name(&style.description) {
-                            Some((mode, true)) if mode == tab.render_mode => {
-                                Some(crate::t!(style.description.as_str()).into_owned())
-                            }
-                            _ => None,
-                        }
-                    }
-                    _ => None,
-                };
+                let style_name = named_visual_style(&tab.scene, tab.render_mode);
                 let bar = viewport_controls(
                     tab.render_mode,
                     self.show_grid,
@@ -1410,7 +1417,7 @@ bg={bg_ms:.1}ms n={view_count}"
                     0,
                     self.render_mode_menu_open,
                     self.render_mode_preview,
-                    None,
+                    named_visual_style(&tab.scene, vp_mode),
                 );
                 let adaptive: Element<'_, Message> = DensitySwap::new(vec![
                     iced::widget::opaque(bar),