English docs policy and Phase 2 DocMark ⇄ DOCX roundtrip

[Copilot]

Project docs were Spanish-only with no English agent contract; Phase 2 (DocMark parse, DOCX write, roundtrip) was still open after Phases 0–1.

Documentation

• Translate AGENTS.md, README, docs/, kb/, corpus/README to English
• Rename design docs to English paths (development-plan, architecture, docmark-specification, technical-analysis, spikes)
• Require English for docs and code comments in AGENTS.md; mark Phases 0–2 core closed

DocMark parser (docsai-docmark)

• Add parse / parse_with_base (YAML subset, front matter, body/inlines) as serializer inverse
• Peel paragraph attrs only when whitespace precedes {...} so tight spans round-trip:

**negrita** *cursiva* ~~tachado~~ [subrayado]{.underline}

• Golden serialize(parse(md)) for basic-text, basic-styles, nested-lists

DOCX writer (docsai-office)

• Hand-written OOXML package writer (write_docx); WRITABLE = [Docx]
• Stable LineHeight::Multiple (thousandths) ↔ OOXML auto (240ths) rounding

Convert + CLI

• SUPPORT: Docx/DocMark read+write; bidirectional convert_file
• roundtrip_file → RoundtripOutcome; CLI roundtrip (-o, --json)

Out of scope / known gaps

Floating DrawingML, full footnote parts, text-box fidelity; corpus-wide Office idempotence beyond basic-text. Phase 3 (xlsx) not started.