fix(ui): measure MarkdownView with wrapped label sizes

MarkdownView only applied its wrap width to labels in doLayout, so
measure reported single-line label sizes and a parent flex allocated
too little height, overlapping sibling rows. Apply the wrap width from
the measure constraints as well; doLayout still re-applies the final
arranged width.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: gegnep

src/ui/controls/markdown_view.cpp

@@ -427,6 +427,22 @@ void MarkdownView::clear() {
   }
 }
 
+LayoutSize MarkdownView::doMeasure(Renderer& renderer, const LayoutConstraints& constraints) {
+  // Apply the wrap width before measuring: labels otherwise report single-line
+  // sizes, the parent allocates too little height for the view, and sibling
+  // rows overlap it. doLayout re-applies the final arranged width.
+  float w = width();
+  if (constraints.hasMaxWidth && constraints.maxWidth > 0.0f) {
+    w = constraints.maxWidth;
+  }
+  if (w > 0.0f) {
+    for (Label* label : m_wrappableLabels) {
+      label->setMaxWidth(w);
+    }
+  }
+  return Flex::doMeasure(renderer, constraints);
+}
+
 void MarkdownView::doLayout(Renderer& renderer) {
   const float w = width();
   if (w > 0.0f) {

src/ui/controls/markdown_view.h

@@ -14,6 +14,7 @@ class MarkdownView : public Flex {
   void trackWrappableLabel(Label* label) { m_wrappableLabels.push_back(label); }
 
 protected:
+  LayoutSize doMeasure(Renderer& renderer, const LayoutConstraints& constraints) override;
   void doLayout(Renderer& renderer) override;
 
 private: