wrapAlign only ever came from a file, so a box inserted here stayed at
the left in both modes that leave it in flow. The floating toolbar now
offers left/centre/right for `inline` and `topBottom` (a side wrap names
the side itself) and drops a coordinate placement when one is picked.
DOCX carried neither: `topBottom` now writes wp:align and an as-char box
the w:jc of its rebuilt marker paragraph, both read back on import. ODF
already wrote both. Measured centred at 297px of a 76…718px column, and
rendered through LibreOffice from .odt and .docx alike.