fix(ui): wrap assistant messages to terminal width

- ToMarkdown() received a width param but never used it
- Apply lipgloss.Wrap() after herald-md render to break long lines
- Preserves ANSI styles/colors through the wrapping pass
- Fixes overflow for all markdown paths: assistant messages, tool
  bodies, and overlay text

internal/ui/style/styles.go

@@ -85,11 +85,13 @@ func GetMarkdownTypography() *herald.Typography {
 	return ty
 }
 
-// ToMarkdown renders markdown content using herald-md.
-// The width parameter is currently unused as herald handles wrapping
-// based on terminal width internally.
+// ToMarkdown renders markdown content using herald-md and wraps the result
+// to the given width so that long lines do not overflow the terminal.
 func ToMarkdown(content string, width int) string {
 	ty := GetMarkdownTypography()
 	rendered := heraldmd.Render(ty, []byte(content))
+	if width > 0 {
+		rendered = lipgloss.Wrap(rendered, width, "")
+	}
 	return rendered
 }