Convert text decoration colour in colour profile conversion (#1247)

Found while testing crates/doc/src/colors.rs:30 (TextStyle::for_each_color_mut, used by TextData, Style and Document::map_colors / set_color_profile)

Co-authored-by: Claude Haiku 5.5 <noreply@anthropic.com>

crates/doc/src/colors.rs

@@ -35,6 +35,9 @@ impl Effect {
 impl TextStyle {
     pub fn for_each_color_mut(&mut self, f: &mut ColorVisitor) {
         self.fills.iter_mut().flatten().for_each(|p| p.for_each_color_mut(f));
+        if let Some(c) = self.decoration_look.as_deref_mut().and_then(|l| l.color.as_mut()) {
+            f(c);
+        }
     }
 }
 

crates/doc/src/colors_tests.rs

@@ -134,3 +134,11 @@ fn profile_and_presets_serialize_only_when_set() {
     assert_eq!(back.color_profile, ColorProfile::DisplayP3);
     assert_eq!(back.image_presets, d.image_presets);
 }
+
+#[test]
+fn text_decoration_colour_is_visited() {
+    let mut s = TextStyle::default();
+    s.set_look(|l| l.color = Some(RED));
+    s.for_each_color_mut(&mut |c| *c = Color::BLACK);
+    assert_eq!(s.look().color, Some(Color::BLACK), "decoration colour not visited");
+}