PR-triage skill: promote likely-addressed PRs with reviewer ping

[potiuk]

Adds a new suggested action mark-ready-with-ping for the case
that today routes to plain ping: a PR's only outstanding
signal is unresolved review threads from collaborators. When a
cheap batch-query heuristic shows the author has likely
addressed each thread (in-thread reply or post-comment commit,
plus the latest commit post-dates the most recent unresolved
thread), the skill proposes promoting the PR to
ready for maintainer review and posting a single ping comment
that invites the original reviewer(s) to confirm and resolve
their threads.

The heuristic is conservative: false-negatives degrade to the
existing plain ping behaviour; false-positives self-correct
on the next round-trip because the comment explicitly invites
the reviewer to push back. The new action shares the same
mandatory pre-mutation guard as mark-ready (refuse if any
workflow run is in action_required for the PR's head SHA).

Files touched:

• fetch-and-batch.md: widen reviewThreads.nodes.comments
  from first: 1 to first: 5 so the heuristic can see
  in-thread author replies without per-PR follow-up queries.
• classify.md: document the
  unresolved_threads_only_likely_addressed sub-flag; update
  the required-fields checklist.
• suggested-actions.md: split the unresolved-threads-only
  rule into two; new "Choosing between ping and
  mark-ready-with-ping" section.
• actions.md: new mark-ready-with-ping recipe; extend the
  order-of-operations recap.
• comment-templates.md: new mark-ready-with-ping body;
  added to the AI-attribution-footer always-include list.
• SKILL.md: extend Golden rule 1b so the workflow-approval
  guard explicitly covers mark-ready-with-ping; add to the
  Step 3 default-action table and Step 4 group ordering.
• interaction-loop.md: insert the new group ahead of plain
  mark-ready so all label-add proposals run back-to-back;
  add safe override (mark-ready-with-ping → ping); extend
  the session summary.

Was generative AI tooling used to co-author this PR?

• Yes — Claude Opus 4.7 (1M context)

Generated-by: Claude Opus 4.7 (1M context) following the guidelines

[choo121600]

lgtm :)