- _merge_inline_marker_columns: skip merge when ≥50% of words are
alphabetic (preserves "to", "in", "der" columns)
- Rule 2 (oversized stub): widen to ≤3 words / ≤5 chars (catches "SEA &")
- IPA phonetics: map longest-avg-text column to column_en so
fix_cell_phonetics runs in the grid editor
- ocr_pipeline_overlays: add missing split_page_into_zones import
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Extracted 4 overlay functions (_get_structure_overlay, _get_columns_overlay,
_get_rows_overlay, _get_words_overlay) that were missing from the initial
split. Provides render_overlay() dispatcher used by sessions module.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
