feat(ui): show ribbon command icons in menus and suggestions

The ribbon definition beside each command stays the one source of its
label and icon. One cached lookup (modules::registry::ribbon_commands)
walks the core ribbon and the expanded Draw/Modify panels; the shortcut
list, the right-click menu, the grip menu and the command-line
suggestions read it.

- Context menu: command rows carry their ribbon icon; Undo/Redo and
  Isolate use interface glyphs, Draw Order its ribbon icon; icons and
  the caret fade on disabled rows.
- Grip menu: Stretch, Move, Rotate, Scale, Mirror and Copy icons.
- Suggestions: an icon column, aligned when a command has none.
- Shortcut list: dropdown entries were read as (label, command) though
  the ribbon stores (command, label), so they never got a label or icon.

Reworked from #1449.

Co-Authored-By: MarcelP102 <30177694+MarcelP102@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/icons.rs

@@ -314,6 +314,15 @@ pub fn semantic<'a, M: 'a>(bytes: &'static [u8], size: f32) -> Element<'a, M> {
     })
 }
 
+/// [`semantic`] faded like disabled menu text.
+pub fn semantic_disabled<'a, M: 'a>(bytes: &'static [u8], size: f32) -> Element<'a, M> {
+    Element::new(SemanticIcon {
+        bytes,
+        size,
+        opacity: 0.42,
+    })
+}
+
 fn semantic_handle(bytes: &'static [u8], theme: &Theme) -> svg::Handle {
     let key = SemanticCacheKey {
         address: bytes.as_ptr() as usize,
@@ -654,6 +663,14 @@ pub fn zoom_icon() -> &'static [u8] {
     NAV_ZOOM
 }
 
+pub fn undo_icon() -> &'static [u8] {
+    UNDO
+}
+
+pub fn redo_icon() -> &'static [u8] {
+    REDO
+}
+
 /// Layer visibility icon bytes (on / off).
 pub fn layer_visible(visible: bool) -> &'static [u8] {
     if visible {
@@ -709,6 +726,10 @@ pub fn themed_disabled_arrow_down<'a, M: 'a>(size: f32) -> Element<'a, M> {
     themed_disabled(TRI_DOWN, size)
 }
 
+pub fn themed_disabled_arrow_right<'a, M: 'a>(size: f32) -> Element<'a, M> {
+    themed_disabled(TRI_RIGHT, size)
+}
+
 pub fn themed_home<'a, M: 'a>(size: f32) -> Element<'a, M> {
     themed(HOME, size)
 }