ci: gate skip-notice on opened/reopened only

CodeRabbit minor finding on the paired canonical PR
(VyOS-Networks/vyos-docs-opus-reviewer#14): the `Notify on PR (when
skipping)` step posts a fresh `gh pr comment` on every `synchronize`
event. On a fork PR to a repo where the AI-validation secrets are not
configured, every push during PR iteration would duplicate the skip
notice, flooding the conversation thread.

Gate the step to fire only on `opened`/`reopened` — those are the
moments where the PR author benefits from being told once that
validation is skipped. Further pushes add no new information; the
workflow-run-page `::notice::` annotation is still emitted on every run
for maintainers.

`concurrency.cancel-in-progress: true` alone is not sufficient — most
synchronize events would be cancelled before the notify step ran, but
any run that completed the notify step before the next push still
posts the comment.

Paired canonical commit: VyOS-Networks/vyos-docs-opus-reviewer@ea88567

0 files changed, 0 insertions, 0 deletions