Centralize configured publication exports in Rust

[Iktahana]

Summary:

• Move export-profile resolution, page-size data, DOCX and EPUB generation, and PDF print-profile logic into Rust.
• Reduce JavaScript packages to thin adapters and remove duplicate generators.
• Add Open XML SDK, LibreOffice, EPUBCheck, PDF.js, and Nu HTML contracts.
• Gate contracts on every platform job and releases on complete CI.

Local verification:

• Node unit tests, typecheck, coverage, and publishable consumer install passed.
• Rust 54 unit plus 8 platform tests, fmt, clippy, and coverage gates passed.
• Python 19 tests at 100% coverage; Android dual-ABI build and Kotlin coverage passed.
• Contracts passed: 65 DOCX plus 9 specified Word-limit rejections, 7 LibreOffice imports, 74 PDF, 7 EPUB, and 3 HTML.

Rust crate release: mdi-core 2.0.4. npm patch versions are computed only after complete CI succeeds on main.

[codecov]

Codecov Report

❌ Patch coverage is 97.29862% with 55 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
mdi-core/src/publication_profile.rs	96.67%	30 Missing ⚠️
mdi-core/src/lib.rs	96.31%	16 Missing ⚠️
mdi-core/src/docx.rs	98.77%	8 Missing ⚠️
nodejs/packages/mdast-util-mdi/src/source.ts	96.77%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!