PR #138 added the issue.comment alias and example grants. Add the
forward-direction separation guards the migration decision requires:
gitea.issue.comment never implies issue close, PR review/approve/merge,
or branch push / repo commit; gitea.pr.comment never implies
gitea.issue.comment; the pre-#137 live author op set still fails closed
with the exact operator-facing reason; and the shipped v1/v2 example
configs keep granting issue comments while preserving author/reviewer
role separation.
Refs #137, #139
Co-Authored-By: Claude Fable 5 <[email protected]>