The detect_merged_cells function was implemented but not exported from
the table module, making it inaccessible to library users. This commit
adds the function to the public API exports.
Also adds a verification note documenting the complete implementation
and the export fix.
Acceptance criteria status:
- All 6 merged cell detection tests pass
- Public Cell.rowspan/colspan fields exist with default 1
- Absorbed cells are excluded from output
- Bbox of merged cell covers absorbed cells
- Borderless tables NO-OP with diagnostic
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
