//! Text parsers: the link/metadata extractors the text builders wrap.
//! `markdown` extracts body links; `frontmatter` extracts YAML frontmatter links
//! and the metadata block.
/// Combined output from parsing a single file: links + optional metadata.
/// Links are raw strings as they appear in the source — the builder handles
/// normalization (fragment stripping, anchor filtering, URI detection).
/// Trait implemented by the built-in text parsers.