//! RightKit PDF engine: the pure, Tauri-free half of the PDF edit pipeline, extracted from
//! ViewRight's `crates/pdf` (the most mature donor), plus ScrapeRight text extraction and Legion
//! page merge as opt-in features.
//!
//! Every function takes bytes, paths, or in-memory `lopdf::Document`s and returns typed values.
//! Path authorization (the host's file broker) stays in the app; [`commit`] provides the atomic
//! disk write (through `rightkit-fs`) once the host has authorized a target.
//!
//! | module | responsibility |
//! |-----------|-------------------------------------------------------------------|
//! | `model` | wire types: commands, islands, locators, typed `PdfEditError` |
//! | `inspect` | page graph walk: text islands with quads, fonts, source locators |
//! | `font` | bundled + system font catalog, subsetting, ToUnicode |
//! | `compose` | sparse-write composition of edit commands onto fresh bytes |
//! | `save` | candidate verification, single-use save tokens, commit resolution |
//! | `commit` | (feature `edit`) lock, recheck and rightkit-fs replace of a token |
//! | `merge` | (feature `merge`) merge PDFs, select/reorder pages |
//! | `extract` | (feature `extract`) text extraction, whole-document and per page |