feat: implement html-to-word-swift converter

[PsychQuantClaw]

Summary

Restore and finish html-to-word-swift as a proper Layer 3 converter in macdoc.

The current main branch only carries the package manifest / README / CLI wiring from the earlier merge, but the tracked converter source and tests are missing. This follow-up issue lands the actual converter implementation.

Conversion Requirements

• Input: .html
• Output: Word .docx (plus streamed OOXML document XML for DocumentConverter)
• Architecture: direct HTML → Word path using OOXML writer strategy
• Protocol: implement DocumentConverter with StreamingOutput

Layer 1 / Core Dependencies

• SwiftSoup for HTML parsing
• ooxml-swift for DOCX generation
• common-converter-swift (DocumentConverter, StreamingOutput, ConversionOptions)

Implementation Notes

• Map headings, paragraphs, lists, tables, hyperlinks, blockquotes, and preformatted blocks into WordDocument
• Provide convertToFile for .docx output and streaming convert for document XML
• Keep package independent under packages/html-to-word-swift/
• Ensure CLI command macdoc html-to-word works against the restored package source

Test Strategy

• Package-level tests for XML/docx generation, metadata, inline formatting, lists, tables, hyperlinks, and code/blockquote handling
• swift test inside packages/html-to-word-swift

[PsychQuantClaw]

Opened follow-up PR: #53