Document current state of assertion diagnostic context across unmapped glyph test suite. All 145+ assertions have been enhanced with Expected/Found/Why structure. Files covered:
- crates/pdftract-core/src/font/encoding.rs (~50 assertions)
- crates/pdftract-core/tests/unmapped_glyph_names_config.rs (16 assertions)
- crates/pdftract-core/tests/cmap_unmapped_glyphs.rs (~70 assertions)
- crates/pdftract-core/src/font/unmapped.rs (9 assertions)
Verification: notes/bf-lpyhe-assertions.md
Closes: bf-63sxe
