Cover both existing-file (produces link) and missing-file (no link)
cases for __has_embed directives.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
PCH compilation now serializes document links and stores them in PCHState.
The master server merges PCH links with main-file links on DocumentLink
requests, fixing missing links for includes inside the preamble.
Also adds document link support for #embed and __has_embed directives.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>