Release v0.8.0

Summary

Minor release that pulls in upstream oxidize-pdf v2.13.0 and surfaces its new
RAG/AI-pipeline capabilities in the Python bridge:

1. Per-chunk and document-level language detection (upstream #293) — opt-in
   ISO 639-3 detection for chunked text, exposed through
   DocumentChunker.with_language_detection(True), the new DetectedLanguage
   type on DocumentChunk.language, and the DocumentChunker.document_language
   aggregator.
2. Token-efficient chunk serialization (upstream #291) — the new
   TokenEfficientExporter, a compact, fully round-trippable tabular format for
   RAG chunks that roughly halves the serialized-token count versus JSON.
3. JsonExporter — structured JSON export for documents and RAG chunks,
   completing the chunk-export surface alongside the token-efficient format.
4. Ruling-based table detection control (upstream #292) —
   PartitionConfig.prefer_ruling_tables getter plus
   PartitionConfig.without_ruling_tables() to opt out of vector-grid table
   reconstruction in the partition pipeline.

This is a non-breaking, additive change at the API level. Every previously
callable method preserves its signature; the new capabilities are opt-in. The
image-extraction fixes from upstream (#286: /SMask alpha compositing and the
flate compression-ratio false-positive) are inherited transparently through the
version bump with no bridge API change.

Upstream

• oxidize-pdf =2.12.0 → =2.13.0. Pinned exact equality preserved. The
  language-detection feature was added to the dependency's feature set
  (compression, signatures, semantic, language-detection,
  default-features = false) to pull in the pure-Rust whatlang detector that
  backs the new language APIs.
• Upstream 2.13.0 added: ruling-based (vector-grid) table detection wired into
  the partition pipeline (#292), per-chunk/document language detection (#293),
  /SMask soft-mask compositing into RGBA on image extraction plus a flate
  compression-ratio guard fix (#286), and the token-efficient chunk serializer
  with the unifying ChunkExporter trait (#291).

Toolchain

• MSRV raised to Rust 1.88 (from 1.77), tracking upstream 2.13.0's own MSRV
  bump. The 2025 ecosystem migration to edition 2024 plus let-chains made the
  previously declared 1.77 unbuildable through the dependency tree.

Added

Language detection (RAG chunks)

• DocumentChunker.with_language_detection(enabled: bool) — builder that turns
  on per-chunk language detection. Disabled by default; when off,
  DocumentChunk.language stays None.
• DocumentChunk.language — DetectedLanguage | None. Populated during
  chunk_text only when detection is enabled.
• DocumentChunker.document_language(chunks) — static method returning the
  dominant DetectedLanguage across chunks, weighted by chunk content length.
  Returns None when no chunk carries a detected language (including the empty
  list).
• DetectedLanguage — frozen type with code (ISO 639-3, e.g. "eng",
  "spa"), confidence (float in [0.0, 1.0]), and reliable (bool).
  Short or ambiguous text can yield an unreliable detection with an
  effectively-random code; gate routing on reliable.

Chunk exporters

• TokenEfficientExporter — export_chunks(chunks) serializes RAG chunks to the
  #oxct/1 tabular format (header declared once, one tab-separated row per
  chunk); the static TokenEfficientExporter.parse_chunks(serialized) is its
  exact inverse, reconstructing the DocumentChunk list. Parsing raises on a
  wrong version marker, wrong header, or a row whose column count does not match
  the header.
• JsonExporter — export(text) for a simple document object and
  export_chunks(chunks) for a structured chunked_document object
  (type, chunk_count, chunks[]). Constructor takes
  pretty_print (default True) and include_chunks (default False);
  JsonExporter.default() mirrors the upstream defaults.

Partition configuration

• PartitionConfig.prefer_ruling_tables — read-only getter; True by default,
  matching upstream. When enabled, bordered tables are reconstructed from the
  PDF's drawn grid (primary path) and per-page graphics are extracted only for
  pages that have a drawn grid, so table-free documents pay no extra cost.
• PartitionConfig.without_ruling_tables() — builder that disables the
  ruling-based detector; only the spatial detector runs and no page graphics are
  extracted. Chains with the existing without_tables / with_* builders.

Compatibility

Fully backward compatible. All 2038 existing tests pass unchanged; 20 new tests
cover the added surface (language detection round-trips against real
English/Spanish corpora, token-efficient export/parse round-trip,
chunked_document JSON shape, and the ruling-tables flag). mypy and
cargo clippy -D warnings are clean.