- fill_mcs150 now uses auto_regenerate=True so pypdf writes appearance
streams for every text field. Preview/Chrome ignore /NeedAppearances and
were showing blank widgets over the values; generated /AP streams make
the text render in all viewers.
- New verify_mcs150.py reads each widget's /AP /N appearance stream (the
literal drawn glyphs) to confirm expected values actually render, since
the container has no OCR/raster tooling. Exits non-zero on any miss.
