Add markup format option to work queries

[ja573]

Summary

• add optional markup_format keyword support to work_by_id, work_by_doi, book_by_doi, chapter_by_doi, works, books, and chapters
• support the case-sensitive GraphQL enum values JATS_XML, PLAIN_TEXT, HTML, and MARKDOWN
• preserve JATS_XML as the default when the argument is omitted or None
• reject unsupported and injection-like values with ValueError before any HTTP request
• prepare package version 1.2.0 and document the public API

Design

Work-query markup formatting belongs to the nested canonical titles(...) and abstracts(...) selections, not to the root work/works field. The generated endpoint helpers therefore consume markup_format as a field-rendering option and pass a fresh per-request field list through the query layer.

Rendering replaces only field entries exactly matching the canonical top-level title and abstract selections. Biographies, related-work titles, additional resources, awards, endorsements, book reviews, and other rich-text fields keep their existing JATS_XML selections.

No static query definition or shared field list is mutated, so sequential requests, multiple clients, concurrent calls, and tests in any order retain independent formatting.

Verification

• python3 -m unittest thothlibrary.tests.test_queries thothlibrary.tests.test_rest thothlibrary.thoth-1_0_0.tests.tests — 28 tests passed
• python3 -m compileall -q thothlibrary — passed
• git diff --check — passed
• python3 setup.py --version — 1.2.0

Focused coverage proves the default and PLAIN_TEXT rendering for all seven methods, unquoted HTML/MARKDOWN, restricted transformation, pre-request validation, raw and structured responses, and no state leakage.

Live read-only verification

A credential-free check against https://api.thoth.pub used work e0f748b2-984f-45cc-8b9e-13989c31dda4 with raw=True. Both explicit JATS_XML and PLAIN_TEXT calls succeeded. Three non-empty canonical title/abstract values were inspected: the JATS response retained tags, while the plain-text response contained visible text without JATS tags. No mutation was performed.

Release preparation

This backward-compatible public API addition prepares version 1.2.0. GitHub was checked before the bump: no v1.2.0 tag, release-preparation branch, or issue/PR mentioning 1.2.0 existed. This PR does not create a release or publish to PyPI.