- Register imported fonts in photocraft_text::shared() so the app can
re-lay text after edits or DPI changes. Prefer an installed full
family, and register an embedded face under its PostScript name
(key-suffixed when two faces share it) so a subset cannot shadow it.
- Warn that text using PDF-embedded fonts may change font when edited or
reopened; the document format does not carry the bytes yet.
- Reject mirrored text and b == -c matrices; scale the tolerance by the
em size so 90-degree text stays editable. Tests for rotated and
mirrored text.
- Use pdfcer's 0.30 em line tolerance.