Selection tools on the right-edge toolbar instead of contextual tabs

The PDF Underlay and External Reference ribbon tabs are gone. While only
PDF underlays are selected their tools (Display in Monochrome, Create
Clipping Boundary, Remove Clipping, Show Underlay, Enable Snap, External
References, Edit Layers, Import As Objects) sit on the right-edge toolbar,
the switches drawn as on while on; while only xrefs are selected the xref
tools do. Contrast and fade stay in Properties. Toolbar tooltips are
translated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/view/mod.rs

@@ -1601,9 +1601,32 @@ bg={bg_ms:.1}ms n={view_count}"
                 }
             }
 
-            // Paper-space context actions: a right-edge vertical toolbar
-            // (viewport / page setup / plot) instead of a contextual ribbon tab.
-            if is_paper && !tab.is_start {
+            // Selection actions: with only PDF underlays or only xrefs
+            // selected, their tools take the right edge (over the paper-space
+            // tools, which come back when the selection changes).
+            // ponytail: one right-edge toolbar at a time; stack them if both
+            // are ever needed together.
+            let selection_tools = if tab.is_start {
+                None
+            } else if self.ribbon.xref_context() {
+                crate::ui::side_toolbar::view(&crate::ui::ribbon::xref_tools())
+            } else if let Some(ctx) = self.ribbon.underlay_context() {
+                let ctx = ctx.clone();
+                crate::ui::side_toolbar::view_with_active(
+                    &crate::ui::ribbon::pdf_underlay_tools(),
+                    &move |id| match id {
+                        "_PDFULMONO" => ctx.monochrome,
+                        "_PDFULSHOW" => ctx.shown,
+                        "_PDFULSNAP" => ctx.snap,
+                        _ => false,
+                    },
+                )
+            } else {
+                None
+            };
+            if let Some(tb) = selection_tools {
+                viewport_stack = viewport_stack.push(tb);
+            } else if is_paper && !tab.is_start {
                 if let Some(tb) =
                     crate::ui::side_toolbar::view(&crate::modules::layout::paper_space_tools())
                 {