Refresh bundled HTML converter

[chubes4]

Summary

• Refresh the bundled html-to-blocks-converter dependency to include the merged action-row, card-image, and asset metadata support.
• Add BFB public API coverage proving context.asset_metadata reaches H2BC through bfb_convert() and enriches image output.

Verification

• php -l tests/BFBConversionUnitTest.php
• git diff --check
• homeboy test --path . --extension wordpress (27 tests, 360 assertions)

Closes #114.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Refreshed the bundled dependency after H2BC merges, added integration coverage, and ran verification for Chris to review.