Verify footnote markers and definitions form a clean bijection:
every [^N] body marker has a matching [^N]: definition and vice versa;
marker/definition numbers are contiguous from 1;
every definition line carries exactly one backticked conv:HASH.
Only a line-START [^N]: is a definition. A body marker glued to a
list-introducing colon (...two types[^2]:) is still a marker, so we strip
definition lines before scanning for markers rather than excluding any
[^N] followed by :.
Verify footnote markers and definitions form a clean bijection:
[^N]body marker has a matching[^N]:definition and vice versa;conv:HASH.Only a line-START
[^N]:is a definition. A body marker glued to a list-introducing colon (...two types[^2]:) is still a marker, so we strip definition lines before scanning for markers rather than excluding any[^N]followed by:.