Headings applied styling (bold+cyan) as an outer wrapper around the
result of renderInlineTokens. When inline elements like codespan emitted
ANSI resets, the outer heading style was killed and only the default
text style was restored via stylePrefix.
Fix: pass a heading-specific InlineStyleContext into renderInlineTokens
so each text segment gets heading styling directly, and stylePrefix
restores heading style after inline elements.