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/ui/ribbon/context_tools.rs

@@ -0,0 +1,96 @@
+//! Selection-driven tools: while only PDF underlays (or only xrefs) are
+//! selected their actions show on the right-edge toolbar; they go when the
+//! selection changes. Contrast and fade stay in the Properties panel.
+
+use super::*;
+use crate::modules::{ModuleEvent, ToolDef};
+
+/// The switches of the selected underlay (the first one) the toolbar shows
+/// as on.
+#[derive(Clone, Debug, PartialEq)]
+pub struct UnderlayContext {
+    pub monochrome: bool,
+    pub shown: bool,
+    pub snap: bool,
+}
+
+fn tool(id: &'static str, label: &'static str, icon: &'static [u8]) -> ToolDef {
+    ToolDef {
+        id,
+        label,
+        icon: IconKind::Svg(icon),
+        event: ModuleEvent::Command(id.to_string()),
+    }
+}
+
+const CLIP: &[u8] = include_bytes!("../../../assets/icons/xclip.svg");
+
+/// PDF underlay tools: display, clipping, options, layers and import.
+pub fn pdf_underlay_tools() -> Vec<ToolDef> {
+    const FRAMES: &[u8] = include_bytes!("../../../assets/icons/underlay_frames.svg");
+    vec![
+        tool("_PDFULMONO", "Display in\nMonochrome", FRAMES),
+        tool("_PDFULCLIP", "Create Clipping\nBoundary", CLIP),
+        tool("_PDFULUNCLIP", "Remove\nClipping", CLIP),
+        tool("_PDFULSHOW", "Show\nUnderlay", FRAMES),
+        tool(
+            "_PDFULSNAP",
+            "Enable\nSnap",
+            include_bytes!("../../../assets/icons/snap_underlays.svg"),
+        ),
+        tool("EXTERNALREFERENCES", "External\nReferences", crate::ui::icons::FOLDER_OPEN),
+        tool(
+            "ULAYERS",
+            "Edit\nLayers",
+            include_bytes!("../../../assets/icons/underlay_layers.svg"),
+        ),
+        tool(
+            "_PDFULIMPORT",
+            "Import As\nObjects",
+            include_bytes!("../../../assets/icons/cui_import.svg"),
+        ),
+    ]
+}
+
+/// External reference tools: edit, open, clipping and the palette.
+pub fn xref_tools() -> Vec<ToolDef> {
+    vec![
+        tool(
+            "_XREFEDIT",
+            "Edit Reference\nIn-Place",
+            include_bytes!("../../../assets/icons/edit_block.svg"),
+        ),
+        tool("_XREFOPEN", "Open\nReference", crate::ui::icons::FOLDER_OPEN),
+        tool("_XREFCLIP", "Create Clipping\nBoundary", CLIP),
+        tool("_XREFUNCLIP", "Remove\nClipping", CLIP),
+        tool("EXTERNALREFERENCES", "External\nReferences", crate::ui::icons::FOLDER_OPEN),
+    ]
+}
+
+impl Ribbon {
+    /// The selection context: the selected underlay's switches, or that
+    /// only xrefs are selected, or neither.
+    pub fn set_underlay_context(&mut self, context: Option<UnderlayContext>, xref: bool) {
+        self.underlay_ctx = context;
+        self.xref_ctx = xref;
+    }
+
+    pub fn underlay_context(&self) -> Option<&UnderlayContext> {
+        self.underlay_ctx.as_ref()
+    }
+
+    pub fn xref_context(&self) -> bool {
+        self.xref_ctx
+    }
+
+    /// Select a tab by its module id.
+    pub fn select_by_id(&mut self, id: &str) -> bool {
+        match self.modules.iter().position(|m| m.id() == id) {
+            Some(index) => {
+                self.select(index);
+                true
+            }
+            None => false,
+        }
+    }
+}