feat(ribbon): the layer combo shows typical layer names in full

The closed combo is at least 250 px wide (about 25 characters of name)
and its dropdown 300 px.

Fixes #1648

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

src/ui/ribbon/mod.rs

@@ -1129,9 +1129,9 @@ impl Ribbon {
             .spacing(2),
         )
             .style(popup_panel_style)
-            .width(Length::Fixed(220.0));
+            .width(Length::Fixed(300.0));
 
-        let (align_right, h_pad, top) = self.dd_anchor(LAYER_COMBO_ID, 220.0, win.0);
+        let (align_right, h_pad, top) = self.dd_anchor(LAYER_COMBO_ID, 300.0, win.0);
         let positioned = position_ribbon_dropdown(panel.into(), align_right, h_pad, top);
 
         Some(dropdown_backdrop(positioned))

src/ui/ribbon/widgets.rs

@@ -996,7 +996,9 @@ pub(super) fn render_large<'a>(
             let tools_w = tool_count * TOOL_BUTTON_W
                 + (tool_count - 1.0).max(0.0) * TOOL_SPACING
                 + GROUP_PADDING;
-            let combo_w = (LARGE_W * 2.5).max(tools_w);
+            // Wide enough to read a typical layer name (about 25 characters)
+            // in the closed combo.
+            let combo_w = (LARGE_W * 2.5).max(tools_w).max(250.0);
 
             let info = layer_infos.iter().find(|l| l.name == active_layer);
             let lc = info.map(|l| l.color).unwrap_or(Color::WHITE);