Two complementary tests for the Type0/CID Latin-1-fallback guard:
1. Tighten `test_identity_h_no_tounicode_suppresses_garbage` on the
existing real-PDF fixture `shinagawa_identity_h.pdf` to also assert
the pre-suppression text contains U+FFFD and contains no high-Latin-1
chars. Pins down WHICH mechanism is suppressing the garbage so a
future regression that re-enables Latin-1 mojibake fails loudly here
instead of silently switching the suppression chain back to
`is_cid_garbage` + high-Latin-1 detection.
2. Add `test_synthetic_type0_broken_tounicode_emits_fffd_not_latin1_mojibake`
with a fully-synthetic Type0 / Identity-H PDF built in process. We
control the malformed ToUnicode contents, the descendant CIDFontType2
shape (just enough for `parse_type0_widths` to set `is_cid=true`,
which is what the new guard keys off of), and the Tj byte stream.
No fixture file or external license needed. Reproduces the exact
"Type0 + non-ASCII bytes + unparseable ToUnicode" code path that
produced the production mojibake samples.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
