Third gate finding: the table-row predicate accepted ANY pipe-wrapped line, but
the downstream table parser only accepts a run of pipe-lines whose SECOND line
is a separator. So pipe-delimited prose such as '| note<br># heading |' was
treated as a table row and kept its literal <br>, silently losing heading/list
rendering that master renders correctly.
The guard now classifies complete blocks with the parser's own grammar
(row regex + separator check) and converts <br> on every unclassified line.
Verified: all non-table cases now match master byte-for-byte, while genuine
multi-row tables keep <br> in every data cell.
Co-authored-by: JayaMegelar <JayaMegelar@users.noreply.github.com>
