Configuration for a single parser under [parsers].
Supports shorthand (markdown = true) and expanded table form
([parsers.markdown] with fields). Parser-specific options go
under [parsers.<name>.options] and are passed through to the parser.
Compile a list of glob patterns into a GlobSet. Returns None if patterns is empty.
Uses literal_separator so * matches a single path component (like shell globs)
and ** matches across directory boundaries.