_INN_RE now requires an explicit ИНН/inn keyword anchor (case-insensitive) within
~20 chars before a 10/12-digit block. Bare digit sequences without the keyword are
no longer candidates — eliminates false-positives on large monetary amounts such as
1 200 000 000 (which coincidentally passes the ФНС checksum). Checksum validation
is kept as a second gate to avoid redacting e.g. «ИНН 1234567890» with bad digits.
_inn_repl updated to use match.group(1) (digit-only capture group) instead of the
full match that now also includes the keyword prefix.
7 new regression tests in test_redaction.py: bare large numbers not redacted,
keyword-cued real INNs (10/12 digit) still redacted, bad-checksum + keyword left
intact, latin «inn:» accepted.
